(adsbygoogle = window.adsbygoogle || []).push({}); I've started updating the list so that it says how to finish the challenge, not what the challenge is.
(Kill yourself and one enemy by cooking a grenade) instead of (Misery Loves Company)
I'm not finished updating it yet, but I'm working on it.
If you know a title AND how to unlock it, please tell me!

<3 – Kill yourself and one enemy by cooking a grenade
without throwing it
1bullet2kills – Kill 2 or more enemies with a single
sniper rifle bullet
1st Lt. (Levels)
1st Sgt. (Levels)
2fast – Get 15 kills using sleight of hand
Absentee Killer – Get a game winning killcam with a Sentry
Gun
Accident Prone – Fall 15 feet or more and survive
Airborne – Call in 3 Pave Lows
All Pro – Headshot 2 or more enemies with one bullet
Ambush – Kill 2 or more enemies with a single claymore 25
times
Backfire – Kill an enemy by shooting their own explosive
Backsmasher – Crush an enemy from behind with your riot
shield
Backstabber – Stab an enemyin the back
BAM! – Kill 10 enemies with cooked grenades
Barrett .50cal – Unlock all Barrett .50 cal attachments
Big Bada Boom – Kill multiple enemies with an explosive
laucher with one shot 5 times
Bite The Bullet – Get 1000 kills using Stopping Power
Blindfire – Kill an enemy while you are still dazed by a
flashbang
Bling Bling – Get 450 kills while using Bling
Blood Brothers – Win 15 Team deathmatches
Blood Money – Get 5 paybacks using headshots
Blunt Trauma – Kill 2 enemies with the riot shield melee
attack
Boilermaker – Kill 5 enemies total by destroying cars
Bombshell – Kill an bomb cattier in sabotage or search and
destroy
Boom Boom – Kill at least 2 enemies with one C4 pack 5
times
BOOM! Headshot – Get 25 headshots with an LMG
Booyah! – Kill 2 or more enemies with a single frag
grenade 5 times
Bow Down – Kill 15 enemies while crouching
Bulletproof – Deflect 1000 bullets with the riot shield
Bullseye – Stick 5 enemies with semtax grenades
C4 and After – Kill 15 enemies using C4
Catch Shrapnel – Kill 5 enemies using claymores
Charity Case – Call in 50 airdrops, using Care Packages, Sentry guns, and Emergency airdrops.
Chick Magnet – Call in 2 EMP's
Cloak and Dagger – Kill 5 enemies with throwing knives
Close Support – Get 250 killstreaks while using hardline
Companion Crate – Call in 25 Care Pckages
Completely Numb – Using painkiller, take enough damage that you would normally die.
Concussive Barrage – Kill an enemy by hitting him with a stun grenade
Counterintelligence – Get 250 close-range kills using scrambler
Crackin’ Skulls – Kill 25 enemies with headshots with an assault rifle
Darkbringer – Darkbringer (Equipment)
Deadline – Hardline Pro V (Perks)
Destroyer – Search And Destroy Victor I (Operations)
Dictator – Dictator (Precision)
Dish the Rock – Point Guard I (Basic Training)
Dishes are Done – Break The Bank (Payback)
Disruptor – Scrambler Pro I (Perks)
Double Down – Bling Pro I (Perks)
Drifter – Vandalism (Basic Training)
Dronekiller – Dronekiller (Finishing Moves)
Droppin’ Crates – Droppin’ Crates (Finishing Moves)
DZ Clear – Air-Mail I (Killstreak)
Early Detection – Bomb Prevention I (Operations)
End of Line – End Game II (Killstreak)
Enemy With Benefits – Group Hug (Precision)
Excalibur – Comando VI (Perks)
Explosive Ordinance – Search And Destroy Victor II (Operations)
Faceoff – Assault Expert I (Precision)
Finishing Touch – Finishing Touch (Finishing Moves)
Fire and Forget – Sentry Veteran II (Killstreak)
Flatliner – The Brink (Elite)
Flying Tank – 21 Ton Giant II (Killstreak)
Flyswatter – Flyswatter (Basic Training)
FNG (Levels)
Frag Out! – Grenade Kill I (Equipment)
Full Force – Danger Close I (Perks)
Full Throttle – Helicopter Inbound (Killstreak)
Get Real – Hardcore Team Player I (Operations)
Ghille in the Mist – Ghille in the Mist II (Basic Training)
Ghostrider – Air To Ground II (Killstreak)
Givin’ Static – Interference I (Killstreak)
Global Thermonuclear War – End Game I (Killstreak)
Godhand – AC130 Veteran I (Killstreak)
Grassy Knoll – Ghille in the Mist I (Basic Training)
Hands Free – Sentry Veteran I (Killstreak)
Hard Target – Airbourne (Precision)
Hard To Kill – Last Stand Pro I (Perks)
Hardcore Only – Hardcore Team Player II (Operations)
Headrush – SMG Expert I (Precision)
Heartbreaker – Scrambler Pro V (Perks)
High-Caliber – Stopping Power Pro I (Perks)
Highlander – Flawless (Precision)
Hired Gun – Counter-C4 II (Elite)
Hot Shot – Defuser I (Operations)
How The ? – How The ? (Elite)
I.C.E. Man – Counter-C4 I (Elite)
ID Thief – Identity Theft (Payback)
I’m Rich – I’m Rich I (Payback)
Impaler – Comando I (Perks)
Intergalactic – Sabotage Victor II (Operations)
Iron Lungs – Steady Aim V (Perks)
It’s Personal! – It’s Personal! (Equipment)
It’s Sabotage! – Sabotage Victor I (Operations)
Jack In The Box – Jack-in-the-Box I (Equipment)
Joint Ops – Point Guard II (Basic Training)
Juggernaut – Solid Steel II (Equipment)
Jump Jet – Vertical Takeoff I (Killstreak)
K Factor – Stopping Power Pro V (Perks)
Kill for Good – Multi-RPG II (Precision)
Kleptomaniac – Renaissance Man [Get a kill from 2 different picked up weapons] (Hidden)
Last Resort – Last Resort (Finishing Moves)
Lights Out! – Think Fast Flash (Humiliation)
Live Long… – Survivalist (Elite)
Living Dead – Living Dead [Final Stand, Get up after getting put into Final Stand] (Hidden)
Lone Wolf – Free For All Victor I (Operations)
Low Profile – Prone Shot II (Basic Training)
M4A1 – M4A1 Mastery (Primary Weapons)
Mach 5 – Mach 5 (Precision)
Mad Men – Bang For Your Buck I (Payback)
Maj. (Levels)
Martyr – Afterlife [Martyrdom, Kill someone with your Deathstreak (Hidden)
Mastermind - Claymore Shot II (Equipment)
Money Shot! - Money Shot (Payback)
NBK - NBK (Precision)
New Jack - ATM (Payback)
Ninja - Comando V (Perks)
Noob Tuber - Ouch (Humiliation)
Not in the face! - LMG Expert I (Precision)
OG - OG (Finishing Moves)
OMFG - Cruelty (Humiliation)
Omnipotent - Radar Inbound I (Killstreak)
Overwatch - Exposed I (Killstreak)
owned. - Owned (Finishing Moves)
Parting Gift - Clay-More I (Precision)
Perfectionist - Perfectionist (Precision)
Philanthropist - Special Delivery II (Killstreak)
Pin Puller - Multi-Frag II (Precision)
Pineapple Express - Grenade Kill II (Equipment)
Plastique - C4 Shot I (Equipment)
Pop Off - SMG Expert II (Precision)
Preemptive Strike - Hardline Pro I (Perks)
Pro Gambler - Airdrop Inbound II (Killstreak)
Protect and Serve - Sponge I (Primary Weapons)
Public Enemy - MVP Team Deathmatch (Operations)
Pushin’ Daisies – Goodbye (Basic Training)
Pyromaniac – Backdraft I (Basic Training)
Quickdraw - Fast Swap (Elite)
Rainmaker - Overdraft (Payback)
Re Zero - Ghille in the Mist III (Basic Training)
Reign Down – Attack Helicopter Veteran I (Killstreak)
Rejected – Backdraft II (Basic Training)
Reloaded - Scavenger Pro I (Perks)
Remote Viewer – X-Ray Vision I (Basic Training)
Rival - Rival (Humiliation)
Robin Hood - Robin Hood I (Payback)
S.S.D.D. (Levels)
Sgt. (Levels)
Share Package - Special Delivery I (Killstreak)
Shot Down – Crouch Shot I (Basic Training)
Sidekick - Sidekick - [5 kills with Secondary/Attachments/Equipment in a life] (Hidden)
SIGINT – Interference II (Killstreak)
Silence – Did you see that? (Equipment)
Skeet Shooting – Hard Landing (Humiliation)
Smash Hit – Smasher (Primary Weapons)
So Baked – Master Chef I (Elite)
Solid Steel – Solid Steel I (Equipment)
Speed Demon – Lightweight I (Perks)
Squawk Box – Attack Helicopter Veteran II (Killstreak)
Stickman – Stickman (Finishing Moves)
Streaker – Fearless (Precision)
Stuck on You – Plastered II (Equipment)
Stun Gun – Slow But Sure (Humiliation)
Submit To Authority – X-Ray Vision II (Basic Training)
Sureshot – Steady Aim I (Perks)
Surgical – The Surgical (Precision)
TacDel – Tactical Deletion (Equipment)
Ta-Da! – Jack-in-the-Box II (Equipment)
Tag! You’re it! – Hot Potato I (Humiliation)
Take A Stab – Carnie II (Equipment)
Tango Down – Prone Shot I (Basic Training)
Team Player – Team Player I (Operations)
The Anarchist – Multi-C4 II (Precision)
The Bomb – Bomb Defender I (Operations)
The Dictator- Have every bullet in an LMG clip hit an enemy
The Domino Effect – Dominoes (Elite)
The Feared – Free For All Victor II (Operations)
The Invincible – Invincible (Elite)
The Legend – Last Man Standing (Operations)
The Mad Bomber – Saboteur I (Operations)
The Mastodon – Star Player (Elite)
The Specialist (Levels)
The Watchman – Radar Inbound II (Killstreak)
Think Fast! – Think Fast (Humiliation)
Time is Money – Time Is Money I (Payback)
Time on Target – Airstrike Veteran I (Killstreak)
To The Extreme – MVP Team Hardcore (Operations)
Toxic – Radiation Sickness [Get Nuked] (Hidden)
Trackstar – Marathon Pro I (Perks)
Transformer – Transformer (Finishing Moves)
Unbelievable – Unbelievable (Finishing Moves)
Unbreakable – Unbreakable I (Primary Weapons)
Voyeur – Exposed II (Killstreak)
Wargasm- Three killstreak rewards in less than 10 seconds (thanks Valimen)

You are missing one.... Wargasm. You unlock it by calling three killstreak rewards i less than 10 seconds. You might consider adding it to the list.

it has been posted before, although not the full list (which by the way yours isnt either, your missing a few)

and might i suggest changing the title or adding more info to each title, as its not really telling you how to unlock the titles at all, its just a reference

Added in Wargasm.
@Dub Zee: Don't really understand you... r u saying that instead of:
<3 – Misery Loves Company (Humiliation)
I should put
<3 – Blow oneself up with a grenade
?

Some other ones missin off the top of my head:

Rollin Thunder
MVP Assassin
The Dictator

No I think the descriptions are good enough. You obly get the callsigns after you unlock its challenge so just by putting the name of the challenge people should figure it out. And yes you are missing quite a few of them, keep updating your thread.
You might want to add all the other rank ones like commander.(Which you are also missing)
(Got to admit the Wargasm one is pretty funny xD)

-Vali

yes pickle, add how you get each one, this will make it easier for people to get the titles they need

lol all right, I'll try.

And yes, wargasm is funny

I am willing to help you in completing your list so I am providing you with a list that contains almost all of the callsigns(Saying almost because I am not sure if those are all of them) and how to unlock them, so that you can complete your list.

You must login or register to view this content.

(Hope It is not advertising)

-Vali