Sounds HOT NASTY AND WILD to me!
If you really need a label, you can always create one! A friend and I recently dubbed mutual ass eating " *69 ". In a sex-repressed society, we have to make it up as we go sometimes.
The next time I see a couple fucking I may have to ask them if my mouth can get involved... Does sound super hot. I have definitely eaten a guy's ass or licked his balls while he fucks one of my girlfriends but I've never really tried to work on both parties at once... which sounds really hot...