While I was in London I bought a board game called Cash and Guns. Tonight we got to play it. The game is set in the aftermath of a successful heist. The gang is gathered to share out the loot, but it seems there is no honour amongst thieves. So everybody gets to try and stick each other up to get the richest pickings. It's a fast moving game of risk taking and score settling. Each player gets a foam gun to point at the other players and you can shout "Banzai" at crucial points in the gameplay.
It is a riot. We played it with 7 players (the maximum is 8) and it worked really well. I think it would be less fun with four though.