Green’s Dictionary of Slang

multiple sex involving a single women and several men; thus as v.

1974		(con. 1940s) E. Thompson Tattoo (1977) 70: ‘Choo-choo you around the bend any day,’ Glenn cracked. ‘Whooo! You and whose army?’ the woman hooted.
1975		J. Wambaugh Choirboys (1976) 305: If there’s gonna be a choo choo, I better see Whaddayameean Dean first.