I was with my grandpa and dad at a game as a teenager. I was being recruited by Wyoming and BYU out of high school, but after seeing the despicable, and I mean despicable behavior of so many Wyoming fans, it was easy to eliminate Wyoming from my options. My grandpa and our group received verbal harassment and ridicule for cheering for BYU from the stands. Just regular cheering, not over the top.
I've got friends who went to Univ. of Wyoming and we mostly good-naturedly rib each other. They're pretty mellow about BYU. But there is a real deep-seated hatred for BYU with a portion of Wyoming's fan base, even after all these years of mostly never playing each other. I've seen it up close and personal and it can be quite ugly. Regardless of the 0-2 start to their season, their fans will be doing what Wyoming fans do for the BYU game.