I've found that the chicks that you have to talk into it are only doing it to please you, but usually end up crying and stopping the whole thing. Mentally stoked on anal acceptance, sexually bummed as crying females typically aren't cool to helping you finish at that point. the one chick that was into it (which i knew ahead of time), started nice and tight but relaxed as we progressed leaving me hammering the hell out her loose anus. although, she knew how to work that anus when my time came, and there aint nothing like coming in a chick's* ass. and she had nipples like earplugs, you could twist and squeeze them as much as you like and they would pop back to normal.
*or maybe a dude's(?), ask GAY or sleepy pancakes....