If this were in English, I'd have expected a donkey joke at some point. Too bad that particular pun doesn't translate into Japanese.
Depends which brand of English you mean, here in the UK we don't really call them anything except donkeys these days. Ass is soooooo 19th century.
Muscle pain?That's just from not working your body out regularly, isn't it, Commander.Tell us all the details!You as well, Admiral?
My tush gets smacked all the time too from my falling over!Who's the one stickin' it up your pipe?
Can I use it as material for my next new book?We've got Borragi*ol, yes.
Hemorrhoid cream.