WordNet (r) 3.0 (2006):

get it on
    v 1: have sexual intercourse with; "This student sleeps with
         everyone in her dorm"; "Adam knew Eve"; "Were you ever
         intimate with this man?" [syn: 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]