Definitions for eff
sleep together, roll in the hay, love, make out, make love, sleep with, get laid, have sex, know, do it, be intimate, have intercourse, have it away, have it off, screw, fuck, jazz, eff, hump, lie with, bed, have a go at it, bang, get it on, bonk(verb)
have sexual intercourse with
"This student sleeps with everyone in her dorm"; "Adam knew Eve"; "Were you ever intimate with this man?"
Origin: A phonetic spelling of the letter f (normally spelled ef), the initial letter of the vulgar term fuck. Compare pee.