For as long as humans have been having sex, they've been trying to get in the mood--or get their partners in the mood. And if necessity is the mother of invention, it's no surprise that humans have developed a wide variety of creative solutions for the old "I've-got-a-headache" problem. The most recent solution, of course, is Viagra. But in ancient India, a young man who proved passionless in the sack might have tried goat testicles boiled in milk. Oysters are another common turn-on; the Roman satirist Juvenal was the first to note their seductive qualities. In medieval times, honeyed mead was the equivalent of Bud Lite for loosening up carousing swains. Fresh snake blood is still revered as a stimulant in parts of Asia, as are bat blood, reindeer penises, shark fins and ground rhino horns. And what sad-sack hasn't at least contemplated Spanish Fly? It's not a fly at all, actually, but the dried remains of beetles, which irritate the male urogenital tract, causing a prolonged erection--and potentially causing serious discomfort and even death, according to the Food and Drug Administration.