Porn is protected by the First Amendment.
People willingly do things to each other on film that some may find distasteful. Still: First Amendment.
I hereby say that it isn't torture to a terrorist if people already do it to each other willingly in porn films.
So, an incomplete list of acceptable practices:
Ham and Cheese sandwich.
Eproctophilia / Dutch Oven.
DP (not' 'Disabled person')
And -- of course -- anything that is found in the seminal film 2 Girls 1 Cup.
I am Laslo.