Bruce as Superman... would be really amusing. wink I don't think he can be goo to that degree. As for Clark being Batman... erm... I'll get back to you on that, ok? (*tries to hide a grin*)

Otherwise, I have a story to "sorta kinda" match this challenge:
Mated Mishap

I hope it doesn't scare you guys away... it's a little weird!

Superman: Why is it that good villains never die?
Batman: Clark, what the hell are good villains?
=> Superman/Batman: Public Enemies