The Lupercalia was an annual Roman festival held on February 15 to honour Faunus, god of fertility and forests. Justin Martyr identified Faunus as Lupercus, 'the one who wards off the wolf', but his identification is not supported by any earlier classical sources. The festival was celebrated near the cave of Lupercal on the Palatine (one of the seven Roman hills), to expiate and purify new life in the Spring. This festival's origins are older than the founding of Rome.
The religious ceremonies were directed by the Luperci, the "brothers of the wolf", priests of Faunus, dressed only in a goatskin. During Lupercalia, a dog and two male goats were sacrificed. Two patrician youths were anointed with the blood, which was wiped off with wool soaked in milk, after which they were expected to smile and laugh. The Luperci afterwards dressed themselves in the skins of the sacrificed goats, in imitation of Lupercus, and ran round the Palatine Hill with thongs cut from the skins in their hands. These were called Februa. Girls and young women would line up on their route to receive lashes from these whips. This was supposed to ensure fertility and ease the pains of childbirth. The name of the month of February is derived from the Latin februare, "to purify" (meant as one of the effects of fever, which has the same linguistic root).
The William Shakespeare play Julius Caesar begins during Lupercalia.Now that's a holiday I could get into!