Back to the Future 2:
original
Future Biff: ... Butt-head!
Biff: who are you calling Butt-head, Butt-head?
censored
Future Biff: ... ...
Biff: who are you calling ..., ...d?
Then later Marty goes "lets get our asses back to the future!" and it goes uncensored on tv loo
I love the ABC version of Mallrats
http://www.viewaskew.com/tv/abcrats/