Do you know what a spoof valentine message is called?

A farce Valentine message is called Vinegar Valentine.

Explanation:

This was an opportunity to affront, dismiss or condemn an individual whom you didn't care for. Vinegar valentines were a kind of offending cards. They are enhanced with a personification, and highlighted beneath an offending lyric.

Apparently allowed on Valentine's Day, the personification and ballad is about the type that the beneficiary has a place with—old maid, floozy, man, researcher, and so on.