While i agree that fag hags are good as a sort of passive F in an active MFM session, they're quite happy to sit back and masturbate while the boys enjoy fucking each other - nice to have an audience. But on th otherhand my darling wife loves it we invite a bisex guest to join us provided - she gets well fucked by both men (or all the men), and they MUST cum deep inside her hungry vagina.
This is exactly what you need in a bi 3some - a slut who gets off more on seeing the guys fuck each others assholes than getting a cock in her own cunt! Fag hags make for the best bi sex!