You know, this raises a thought...

I bet Buggy's dick is detached and I bet Alvida has it.

I could have sworn that riding cock in this manner was called thighjob; tag used in at least one previous post.

There's a "thighsex" tag (also "intercrural" which means the same thing), but that's typically when the woman has her thighs pressed together. To me this seems more like nude frottage

The 'grinding' tag has quite a few like this.

This picture actually reminds me of Slim Pickens from Dr. Strangelove.

Hmmmm. Thighsex has also been used only once (right here!). Well, thanks for the suggestions anyway. I can sleep tonight. :-)