Before it was "Christianized" Valentine's Day was a pastoral holiday called "Lupercalia" when two male goats and a dog were sacrificed and salty meal cakes, prepared by Vestal Virgins, were burnt on an alter.
The Lupercalia holiday was pegged to honor Lupa, the she-wolf who suckled the infant orphans, Romulus and Remus who were (it is said), the founders of Rome.
After the two goats and the dog were slaughtered, they were then skinned and whips made from their hides. The whips were then used to lash girls and young women who would line up for the abuse, as the lashings were supposed to ensure fertility, prevent sterility, and ease the pain of childbirth.
Adding a little more fun to the festivities, young men and women would draw lots and be randomly paired for sex.
The "pagan" holiday of Lupercalia was banned in the 5th Century by Pope Gelasius (spoil sport!), but instead of disappearing altogether, it was transformed into a more symbolic celebration of fertility and love, this time with everyone's clothes still on, the goats and dogs unmolested, and the whole thing laid at "St. Valentine's" feet.