basketball games (Andre Miller, Van Horn, Britton Johnsen, Alex Jensen era). Got to go to a few football games (I was there when Kaneshiro doinked the FG).
When I was 11 or 12, I remember watching the BYU-U basketball game on tv, and the whole Huntsman Center chanting "(mekeli) Wesley sucks! Wesley sucks! Wesley sucks!". My friend's dad was swearing at the tv, screaming at BYU more than for his own team. I remember going home that night thinking, "I don't want to be 'that guy'".
The switch started then, August that same year, here comes Doman-Staley. That football season cemented the change.
Funny how I didn't want to be "that guy", and now am very much "that guy". At least it's on the right side of the rivalry though.