my body unfortunately ...and it can be unfortunate if your Dom decides on cum denial! responds very quickly lol and i have in the past cum even when ive been bored stiff just going through the motions with vanillas and barely even felt anything..i also did when i was raped (which is a bit difficult to admit to) and NO i did not enjoy even one second of that!!
so nope ive never had to fake it lol and my body does ''betray'' me however its simply a bodily function and was not connected to any pleasure at those times..it's just body fluid.