The oversexed young male is probably desperate for guidelines, direction, anything, as long as it's not boundaries. Start the junior oversexed young male off with The Game, Neil Strauss' controversial guide to making the ladies love you and your raging hormones. Or else.
For the more advanced Lover, try Art Of Seduction. I should warn you: do not give this book to a sociopath. Apparently, in the wrong hands, this book could wreck many plagues of evils. Locusts. Boils. Legions of men wearing fleece-lined Crocs. Terrible, terrible things. But for a nice boy with no experience, or a woman desirous of crushing her rival (oh! ha), Art of Seduction might learn them a thing or two. Like psychological manipulation. Merry Christmas!
Enough with the mind games. So let's say the giftee talks the talk. But is he any good at walking the walk? Maybe this giftee is your brother, in which case you don't want to know. You probably don't want to know, regardless. However, if you see the giftee on the dance floor and it looks like he's dancing in a barrel with a hundred pissed off snakes, you have a situation on his hands. Try Seymore Butts' Rock Her World for a more hardcore thing. A klassier option would be the Kama Sutra.
Another option would be to learn the oversexed male in the mysterious ways of women. She Comes First actually seems really sweet (and well-researched too). Not sure what's up with that ripe papaya on the cover but...whatever works. For a sympathetic literary ear, Nick Hornby (like About A Boy), Jonathan Tropper (The Book of Joe), Matt Dunn (The Ex-Boyfriend's Handbook) or the endearingly titled Things My Girlfriend And I Have Argued About will work.
Back up gift: 15 minutes, God-given patience and your sweet lovin'. Yiiiick!