to seriously answer this ques.. you yourself might have taken big shit sometime right!? You can feel your botty hole to be loosen up then it goes back to its original shape babe
Muscle reflex?? I dunno I am not a science student reply
There is a difference between popping and prepping for anal. If you shit so big that it "loosened" your asshole, you're likely bleeding from it and in pain. Will always have to prep for anal. reply