If the problem is when the joke lives on amusing undergrads long after you've tired of it, that just makes it worse.

Wait until they hear about what Magpie Lane in Oxford used to be called.

https://en.wikipedia.org/wiki/Magpie_Lane,_Oxford

A historical bawdy pun is one of the most Oxfordian things I can think of. If we can incorporate a man in drag, we're in real business.