I haven't read all the suggestions, soo i have no idea if this idea already said, sorry if it is...
Soo my idea is black cops,
1 Team is all black players, soo the black personages of mw2, the other team is blank. The black team needs a m9 (the gun the police in america use i think) And the other team a weapon they choose. The blank team are the gangsters, they got 1 min the time too deal weapons on drugs in game, after that 1 minute the black team can move, you hear the sound of sirenes of a police car and than the blank team needs too shoot the black team, godmode must be dissabled, and than a search and destroy like gameplay. If you die you can't respawn. The dealing is with an box of the search and detroy, 1 can *sell their weapon* and wait until the other have changed their weapon to that weapon and the guy who *sold* their weapon can pick up the weapon of the other guy, this will be like weapon dealing like. Than the police can come and will shoot the others dead but the gangssters must destroy all the black cops.. and when 1 team is dead the whole game ends and you get to the main menu back.
Thanks for reading, I think its a good idea