Rip your arms off and use it as a club.
Seriously, how badass is that?
I've seen my friend do it single player, but i really wanna see something like this in multiplayer. Well, not just this, but general self-dismemb is really dumb, but some people bring it into badass levels, like those replays where the guy throw his hand and decapt uke like a boss. Maybe there could be a cool event for this?