Actually, it started out as a sophomoric mimic of the "tastes great" - "less filling" Miller ad from years ago. Usually starts up when the band plays Swingtown. The various student sections have insulted each other for years. When I was a student, section O was reserved for freshmen. So the chant was O sucks. The kids in O would chant stuff like, N sucks P back at them. When Michigan, coached by Bo Schembeckler, came to town, the chant was O sucks Bo. So now we have the imfamous FU-ES chant that the administration has been trying to eleiminate for years. The aim of the students is to make it loud enough to be heard on national television.
Just more fun in Madtown.