Green’s Dictionary of Slang

a position of heterosexual intercourse (vaginal or anal) whereby the woman straddles the man; also as v.

1972		B. Rodgers Queens’ Vernacular 171: reverse western (fr pros sl) heterosexual position with the woman straddling the man.
2001		‘Randy Everhard’ Tattoo of a Naked Lady 46: Moving into a reverse cowgirl, she replugged her sopping quiff.
2004		Anal Ecstasy 🌐 Watch her strip down and show off her amazing ass and sphincter. Then watch her reverse cowboy as she sits her asshole in [sic] a schlong for some ass slamming anal sex.
2004		FemaleFirst.co.uk 11 May 🌐 You might try the ‘reverse cowboy’ its when you put your dude on his back and you position yourself on top but with your back on his chest. it has a good angle and feels great. my wife and i do it and it is good for us both.