NOTE: This thread is over 8 months old so these glitches may be patched.
Well there not glitches, I just said that to make more people visit this thread, but they might as well be glitches, so don't worry I havent decieved you. I'm sure some of you will already know these, but this guide is mainly for people who are new to BFBC2.
Engineer XP boost glitch
Ok, so spawn as an engineer.
Then take a quad and drive it into the wall a few times.
When the quad's health is around 20%, get of the quad.
Now repair the quad.
You can earn 80000 xp depending on how long you do this for.
[ame=http://www.youtube.com/watch?v=YfMTfWmOQ-k]YouTube - Battlefield Bad Company 2 : Boost Tutorial (BBC2)[/ame]
Medic XP boost glitch
Ok, so spawn as a medic.
You will need a squad member willing to help you.
Kill your squad member and revive him with the resuscitation kit.
You lose 15xp for killing your squad member, but you gain 80xp for reviving them.
[ame=http://www.youtube.com/watch?v=oMpfMQ1v8cE]YouTube - Battlefield Bad Company 2 : Medic Boost Tutorial (BBC2)[/ame]
Try using this tut too boost you XP. Play rush and when you are on the attacking side run to the back of your spawn so the out of bounds timer comes up. When your team mate goes down revive him and then you go out and die and have him revive you. This way there is no negative xp only +80 for each revive. Read other users coments below. They provide clearer information. Thank you to 51N15T3R for this information. I would like to say thanks to the guys for correcting me.