Green’s Dictionary of Slang

sexual activity involving three people; also as adj.

1972		B. Rodgers Queens’ Vernacular 196: three-way group sex between three participants.
1979		J. Rechy Rushes (1981) 48: I did everything [...] the three-ways, the four-ways — not enough!
1986		J. Ellroy Suicide Hill 83: The ridiculous accounts of three ways and four ways made him want to wretch [sic].
1991		W.T. Vollmann Whores for Gloria 51: Is this some three-way scene? said Dinah. You want me to fuck her or you want more hair or what?
2002		D.H. Sterry Chicken (2003) 133: I always wanted to have a three-way with a nun.
2013		T. Dorsey Riptide Ultra-Glide 223: There, I’m an artist. Thousands of women on ecstasy now want to have three-ways with me.
2021		J. Ellroy Widespread Panic 10: I was Mr Three-Way then. I swung with stewardesses, starlets and stars.