Because nothing says "classy and sophisticated home decor" like a dick joke.
Speaking of classy and sophisticated, here is a charming little number from the darkest recesses of Etsy:
I would make a joke here, but that would only serve to enhance any mental images you might already have, and you don't deserve that kind of treatment. (Just remember, etiquette demands that you keep your pinkie finger up. Up where, etiquette does not say.) Alright, so I made one joke.