Have you ever heard of "vinegar" valentines?
I hadn't, till today.
Thanks to Librarian Maggie, who is a connoisseur of vintage cards.
For some time it was all the rage to send insulting valentines, not only to your sweetheart but to others with whom you had business dealings or other connections.
More nasty valentines to be seen with the following article:
THE CURIOUS TRADITION OF VALENTINE'S DAY HATE MAIL