St. Valentine's Day Massacre
The St. Valentine's Day Massacre occurred on February 14th, 437 AD. A Young Italian man named Saint Valentine (not a saint at the time) decided he was just fucking pissed at the whole world. He bought a knife, and decided to have a massacre. He gleefully slaughtered every man, woman and child in his small town of Venice. After killing everyone in sight, he proceeded to carve the hearts out of the chests of his victims and mailed them to governors of nearby cities warning them not to fuck with him, cause he'll rip your fucking heart out.
However, as fate would have it, Valentine's Ex-Wife Valerie had become mayor of a nearby settlement, and upon receiving the bloody heart of a small child knew that only one person could be fucking crazy enough to send it to her. Because she was an old skanky bitch with sand in her vagina, she decided to lead an army to kill her Ex-Husband, because her allimony that allowed her to buy mayorship just wasn't enough.
She marshalled her troops, and 1 year later, on February 14th 438 AD she arrived in Venice with her army. Valentine's mental state had degraded significantly over the year, and he responded by throwing his own feces at the attacking army. Valerie was struck in the face by a particularly gooey portion, and remembered why she had loved her husband so long ago: because she had a thing for scatology.
Valerie called off the attack and ran to hug her deranged, feces covered husband. Valentine was made a saint by the Catholic Church because they don't believe in divorce, and Valentine getting back with his Ex was considered saintly material (cut them some slack, people aren't perfect).
To honor the events of the massacre and subsequent romantic engagement, we celebrate Valentine's Day by exchanging heart shaped cards and giving chocolate (the practice of throwing feces was changed to chocolate around the 1300s).