(Quite a lot of this comes from Pliny the Elder's wonderfully whacky Natural History
Book 28 which I highly recommend to anyone who is interested in ancient Rome and Greece. It's a wonderful glimpse into what people believed.)
Romans seem to have thought that hyenas were hermaphrodites/or could switch gender (Ovid thinks the females do so right after having sex - no idea where he thought the womb went.). That makes it magical, so its body will have all sorts of magical effects. It was also thought to be sexually voracious, which means that it is very useful in love magic, where by a process of sympathy you could get that appetite transferred to the object of your desire.
Pliny lists 79 remedies from the hyena (I think the max for other animals is 19 and that's for the crocodile). I present a selection:
1. A hyena's anus worn as an amulet will make you irresistible to the ladies - one look and they will follow you. (You call also rub a tick on her groin if that doesn't get her going.)( More 'facts' behind the cut )
(Also, random fact from Pliny the Elder: if you are pregnant never, ever step over a beaver. DISASTER WILL FOLLOW. I don't know why you would step over a beaver, but just in case, forewarned is forearmed! Also the left foot of a hyena hung above a bed will kill a woman in labour. But, don't despair! Eating wolf meat or having someone who has eaten wolf meat sitting beside you helps.)
Also (and this must be the worst birthday gift EVER): I dedicate this to the lovely thedorkygirl
who both have birthdays coming up.