"i can's stand BYU fans" even though BYU fans have hardly paid any attention to them over the years. There is the underlying church thing going on too. For a many BSU fans, the BYU hate is an indirect route of taking a shot at the church.
I'll cheer for BSU. I just can't watch BSU game or a BYU game around my family or friends that are BSU fans. They just can't help constantly taking swipes at BYU even if BYU isn't involved in the game. They are mini-Utes/Aggies.