Borderlands 2, because you can't have any more fun playing games than playing 4 player borderlands with everyone equipping the most beast gun ever to grace a video game,
DOUBLE PENETRATING UNKEMPT HAROLD
The humour banter and smiles borderlands gives you isn't replicated in a lot of games, it's fun to play and even more fun as the guns are downright insane at times...!
There's only one other sight- or should I say sound that can beat that of a team of Salvadors dual wielding double penetrating unkempt harolds. This can only be beat by the one thing, and that one thing being
[spoiler]A full lobby of gunzerkers dual wielding the bane.[/spoiler]