Anal secks

i am a porno freak, i've watched hundreds of videos and pics. but of all the things i've seen: piss fetish
scat
foot fetish
fat chicks
dildos
shower sex
blowjobs
and BDSM

there is still one thing i don't get. How the fuck, when somthing gets stuck up the ass, is the person able to pull it out clean? I get amazed when i see that. please explain.

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