Of course, it was during a BYU-Utah basketball game in the upper level of the Marriott Center — the Utah and BYU fans were going back and forth at each other intensely, and there were plenty of Cougar fans that decided to return like for like. (EDIT: This was in the days before the ROC — I think most were students)

I can't say I've seen it at other BYU games — although I imagine if a visiting fan wants to dish out some salty language toward BYU fans, he/she will find BYU fans willing to give it back. So while I'm sure it happens, I'd be surprised if it rises to the level of "worst experience I've ever had at an away game" for many fans visiting LES or the MC.