Two Way Lunch
A act of sexual deviance in which one individual performs analingus on another, whilst a third member of the group performs cunnilingus/fellatio on the same individual, thus achieving simultaneous oral stimulation of the genitals and anus.
Sally loved to have her buthole eaten, and loved to have her cooter tongued just as much, but Biff was only one man, with one tongue, so Biff and Sally invited Sam to join them for a two way lunch on Sally.