Literary jokes are simultaneously the best and worst jokes.
Books are for nerds. Everyone knows that. Therefore the puns are, you know, horrendous. Just truly awful stuff. The kind of jokes that make you feel like god might really exist and he definitely hates you now for making that joke.
On the other hand, reading is almost always a solitary act. So when you see a joke made about something that feels like only you should know about it, it’s like OMG HELLO ARE YOU MY NEW BEST FRIEND RIGHT NOW?!?
That’s why this Kurt Vonnegut soap works so well. You know, as a thing to keep in your bathroom for other readers to enjoy. It’s probably also some great soap (apparently rosewater scented, as in Mr. Rosewater) but you pretty much have to keep it in the wrapper for the joke to work. So get one of those dishes your mom had for things in the bathroom that nobody is ever actually supposed to use.