The first example I can think of with that is an older gif I made for tumblr, that has sadly been caught by the filters. It was a very sketchy 3 frame gif of someone being fucked by a naga while encased his coils, while he watched from a short distance away.
It had about 3.5k notes before it was wiped off the site, and I was consistently shocked that it ever got that far. I made an improved version of it, still very sketchy, but it's still one of my favourite pieces because I can really feel the squeezing of the coils, and the pulsing of their orgasm from it.

Somehow these tiny versions of the gifs still survive!
https://64.media.tumblr.com/0c42df20134aea0da904bc305158e99a/tumblr_inline_pjupdhF38W1r7dgip_250.gif
https://64.media.tumblr.com/fe08234b8013a4cd3b4174323820cc41/tumblr_inline_pjupdiB3Zc1r7dgip_250.gif