I'd go rent a really really nice car like a lambo or something and crash it on purpose, call up the dealership and be like "hey so I umm crashed your car, how much did that cost?... uh huh, well do you want that in cash or check? and how much for another one?... oh yeah, just so you know I did that on purpose and I think I'm gonna crash this one too, so be ready"

If i ever won that kinda money I'd probably spend it all on doing the wierd and stupid shit I've always wanted to do just because I can finally afford to, and it would bring me happiness... I'd donate a good amount to some good causes too