I want you to consider this now. You're bent over literally backwards. Do you know why that exists as a saying? Why saying that you bent over backwards to do something implies you really put a lot of effort in? Because it's f*****g hard to bend over backwards if you're not made of rubber. And that saying in no way implies that, once you bent over backwards, you let another human climb on and ride you, because clearly that would be insane. The only thing missing to turn this from a sex position into a medieval torture is a bed of hot coals under you.
In practical terms, they could simply call this position "Collapsed Heap Of Shrieking, Broken Dong" and it would be just as accurate a description of what's happening. I have no doubt some yoga masters, gymnasts, and Avengers can do this. I can't.
It's the only possible explanation for why Gwen and MJ stick around.