According to the acronyms listed on this site, it's called "Italian" when you slide your cock back and forth between her butt cheeks. Some call it "Coney Dog" (i.e. dog in a bun). LOL.
Sounds like a lot of fun. Lights dimmed, sexy music playing, lying on the lady's back, reaching around and playing with her breasts, kissing her on her neck while sliding between a couple of well-lubed apple cheeks.
But I don't see it very often in the reviews. Have you tried it? Enjoyed it? How about from the provider's perspective (any objection to feeling a warm finish between the cheeks)?