I was 11 and Utah had come to Provo. When I went for my usual seat, a bunch of younger Utah fans were already there, but I quietly staked out a corner on the upper left.
One of the Utah Fans said “You’re not welcome here bud” but some old BYU guy standing near the bleacher said loudly to me “you just stay there, you’ve got every right to be there” and glared at the Utah fans.
The Utah fans started mixing Bloody Mary’s and got drunk, unruly and profane. Not sure why, but BYU security did not intervene on the alcohol, just when they tried to start fights. Having never seen a drunk person, it imprinted deeply on me, especially as they kept insulting me for my BYU stocking cap. They got beat 27-0 and all they had left was to stomp on the bleacher and tear a couple boards off.
I’d sat with Wyoming fans, Colorado State fans with their cowbells, etc. But Utah fans were in their own category after that for me.