A Strange Card

A few weeks ago, I received a strange and obscene greeting card. I'll spare you the details, but the beginning said, "Horray, horray, it's the 10th of May..." Then, underneath, there were pictures of bunnies. No return address, no name, no signature, nothing personal, postmarked from Minnesota. Any of my peeps send this expecting me to get a joke I obviously have forgotten? Or, did anyone else receive something like this?