MMF is when 2 males and one female have sex in 1 bed at the same time.
Jack: hey Zac,
Jack: wanna come over to my house and have sex?
Zac: with you? your damn gay!
jack: i mean with my girlfriend too...
Zac: you mean that hot chick that gave you that blowjob?
zac: k, ill go
Jack: will you give me a handjob too?
Zac: i knew you were gay! you just wanted to hump me!
Zac: FUCK OFF, BITCH!
Zac: YOU JUST WANT TO DO MMF!