I just wanted to clear something up for everyone who has ever been challenged by which John Hughes movie uses the line "mess with the bull you get the horns".
A: BOTH "Some Kind Of Wonderful" and "Breakfast Club". The confusion, you see, is that Paul Gleason playing Vice Principal Vernon holds up his fingers in a bull horn shape and says "I've got you for two months" which may cause you to wonder if your memory is inaccurate...but it's not. He also said the bull and horns thing.
I guess John Hughes really loves this zinger, and can't help but use it across movies. There is plenty of president for the the practice: Woody Allen has a ton of one liners that migrate across movies, as does Mell Brooks - a "Walk this way" site gag shows up in "Young Frankenstein" and "History Of The World Part I". There are plenty of other examples - Shakespeare for example...he does it.