Lupercalia was a very ancient, possibly pre-Roman pastoral festival, observed on February 13 through 15, to avert evil spirits and purify the city, releasing health and fertility.
Lupercalia subsumed Februa, an earlier-origin spring cleansing ritual held on the same date, which gives the month of February (Februarius) its name.
The name Lupercalia was believed in antiquity to evince some connection with the Ancient Greek festival of the Arcadian Lykaia (from Ancient Greek: λύκος — lukos, "wolf", Latin lupus) and the worship of Lycaean Pan, assumed to be a Greek equivalent to Faunus.
Lupercus is the god of shepherds. His festival, celebrated on the anniversary of the founding of his temple on February 15, was called the Lupercalia. His priests wore goatskins. The Lycaean god, whom the Greeks call Pan and the Romans Lupercus, is often depicted nude save for the girdle of goatskin, and a statue was said to be in the cave where Romulus and Remus were suckled by a she-wolf. There, on the Ides of February (in February the ides is the 13th), a goat and a dog were sacrificed, and salt mealcakes prepared by the Vestal Virgins were burnt.
Plutarch described Lupercalia:
Lupercalia, of which many write that it was anciently celebrated by shepherds, and has also some connection with the Arcadian Lycaea. At this time many of the noble youths and of the magistrates run up and down through the city naked, for sport and laughter striking those they meet with shaggy thongs. And many women of rank also purposely get in their way, and like children at school present their hands to be struck, believing that the pregnant will thus be helped in delivery, and the barren to pregnancy.The rites were directed by the Luperci, the "brothers of the wolf (lupus)", a corporation of sacerdotes (priests) of Faunus, dressed only in a goatskin, whose institution is attributed either to the Arcadian Evander, or to Romulus and Remus. The Luperci were divided into two collegia, called Quinctiliani (or Quinctiales) and Fabiani, from the gens Quinctilia (or Quinctia) and gens Fabia; at the head of each of these colleges was a magister.
In 44 BC, a third college, the Julii, was instituted in honor of Julius Caesar, the first magister of which was Mark Antony. Antony offered Caesar a crown during the festival, an act that was widely interpreted as a sign that Caesar aspired to make himself king and was gauging the reaction of the crowd. In imperial times the members were usually of equestrian standing.
The festival began with the sacrifice by the Luperci (or the flamen dialis) of two male goats and a dog. Next two young patrician Luperci were led to the altar, to be anointed on their foreheads with the sacrificial blood, which was wiped off the bloody knife with wool soaked in milk, after which they were expected to smile and laugh.
By the 5th century, when the public performance of pagan rites had been outlawed, a nominally Christian Roman populace still clung to the Lupercalia in the time of Pope Gelasius I (494–96). It had been literally degraded since the 1st century, when in 44 BC the consul Mark Antony did not scruple to run with the Luperci . Now the upper classes left the festivities to the rabble.
Whatever the fortunes of the rites in the meantime, in the last decade of the 5th century they prompted Pope Gelasius I's taunt to the senators who were intent on preserving them: "If you assert that this rite has salutary force, celebrate it yourselves in the ancestral fashion; run nude yourselves that you may properly carry out the mockery." The remark was addressed to the senator Andromachus by Gelasius in an extended literary epistle that was virtually a diatribe against the Lupercalia. Gelasius finally abolished the Lupercalia after a long dispute.
Some authors claim that Gelasius replaced Lupercalia with the "Feast of the Purification of the Blessed Virgin Mary," but researcher Oruch says that there is no written record of Gelasius ever intending a replacement of Lupercalia.
There seems to be some doubt amongst scholars that there is a connection between Valentines and Lupercalia. Me?? Running naked through the streets and celebrating fertility sounds close enough to drink to ..