I'll be lame and only do NPC because it's what I know best... but I know a bunch of frat guys too.
NPC Sororities
Alpha Chi Omega (x)
Alpha Delta Pi (x, obviously)
Alpha Gamma Delta
Alpha Epsilon Phi
Alpha Omicron Pi (x)
Alpha Phi
Alpha Sigma Alpha (x)
Alpha Sigma Tau
Alpha Xi Delta (x)
Chi Omega (x)
Delta Delta Delta (x)
Delta Gamma (x)
Delta Zeta (x)
Delta Phi Epsilon (x)
Gamma Phi Beta (x)
Kappa Alpha Theta (x)
Kappa Delta (x)
Kappa Kappa Gamma (x)
Phi Mu (x)
Phi Sigma Sigma
Pi Beta Phi (x)
Sigma Delta Tau
Sigma Kappa (x)
Sigma Sigma Sigma
Theta Phi Alpha
Zeta Tau Alpha (x)
18/26 if I counted correctly
