I have several friends who are A&M fans. Individually, they are pretty nice people. Pretty rational football fans, too.
However, when they get together over there, something peculiar happens. The word "cult" is freighted with a lot of pejorative connotations, but somehow something like "a group of people having beliefs or practices regarded by others as strange or sinister" sort of fits. It's usually a small group, though, and there are a LOT of Aggies, so maybe a different word is better.
Given that it's a football board, I'll also mention that my Aggie friends have about had it with the Jimbo show. They have to go to Oxford and LSU still and confidence is waning.