During a BYU/Utah game. Put aside your football fandom, and imagine how the prophet would feel about the anti-Mormon hate & venom you hear....that has nothing to do with the game or football.
I've only done it once (not wearing BYU gear), so maybe the group around me was especially vile, and the MUSS is generally respectful of the church during a BYU game at RES?
Somehow - I think not...