Here are some of the nicknames I know of:
Tri-Delta: Try a Delta, everyone else has!
ADPi: AD Spies (I don't understand that one)
DG: You can't spell dog without DG!
KD: Keg Drainers
Zeta: Zits, Tits, and A$$
Chi-o: Chi-Ho
SAE: Same a$$holes everywhere
Lambda Chi: Rammed a guy
Phi Mu: Phi Mooooooo
Phi Sigma Sigma: Phi Piggy Piggy