you have to go to double xp, hover over yes, then tell ur friend to look for a game den tell him to back out then go to barracks, then go to double weapon xp n press x on yes then another pop up will be there asking to use ur prestige token and press x on yes again then you'll have negative prestige tokens!
Dude, i tried doing it, but it wasted my prestige token.
I think i know what i did wrong. I went to purchase an unlock first, instead of a double xp.
Well, too bad, i have another 65 levels till i get another one....
>.>