Matt and Sean #1, with Jackie Jr. a close second. M&S is self-explanatory I think, since they were stupid enough to beat the shit out of that stockbroker, not to mention all the stuff with Tony, plus thinking that whacking Chris would have helped them get ahead.

Jackie Jr. is a close second because of his attitude and basically telling everyone in earshot that his dad used to run the Jersey mob. I love the scene where he acts like Don Corleone with Matush the drug dealer. Plus he was a scumbag since he tried to date rape Meadow and looks down her shirt when she's passed out. While I think he should have been kept alive longer (he made a good comparison to AJ), he was pretty stupid in thinking he could get away with the shit he did.