Not that I'd advocate this of course, but the Crash jQuery Plugin is there to use if you need to for some reason.
Seriously though, crashing someone's browser isn't cool, cause lets be honest, the people that are still running ie6 are either a) people like your grandmother who doesn't know any better, or b) people have have to because they work with some sort of antiquated company or software that requires it.
Course, these people aren't going to be surfing to sites that will have jQuery enabled anyway....