I went to the BYU @ Oregon State game in 2011. It turned out to be a great game in which BYU had a dominant win. Cody Hoffman was great, and KVN had an awesome game as well.
However, a few seats in front of us sat two rather husky young (20 something) gals, one brunette sporting an OSU hoodie and the other, a blonde, decked out in Utah gear. Very weird, honestly, and clearly out of place.
Periodically throughout the first half or so, the Utah fan gal would yell something anti-BYU, like "Go back to Provo" or "Zoobies" or something like that.
What was particularly funny was that she acted like she was expecting the other OSU fans around her to join in (as if everyone should hate BYU as much as she does, and everyone knows that BYU fans are called Zoobies, or whatever other Utah fan language she was babbling). But mostly the OSU fans just ignored it--at least partly because BYU was dominating on the field.
They left after the 3rd quarter. I laughed when they disappeared.
But a takeaway could be that if birds of a feather flock together, at least one OSU fan is similar to a Utah fan, in that they flock together. On the other hand, to the credit of other OSU fans, they mostly ignored the crazy lady in Utah gear screaming anti-BYU blabber (most of which was probably incoherent to them, unless they speak Utah fan gobbledygook).