When you wank your dick so hard that when you finally squirt your sperm everywhere your so tired that you decide to take a quick nap.
Make sure you clean yourself up before you take the nap or do it in a private area, otherwise someone may walk in and find you completely naked with a flaccid red dick and your stomach covered in sperm.
Mum: I think our son had a wetdream
Dad: Naaahh look how raw his dick his, he probably had a wild wank and was so tired afterwards he fell asleep.
Mum: Ahhhhh a Fap'n'Nap
Dad: Thats right
A classic fap'n'nap combo is usually combined in men ages 20-40 before they take their afternoon nap.
Man one: Hello is anyone in this thread?
Man two: I am the only one here, But im off for an ol' favorite... The Fap'n'nap
Man one: Better make that the power fap'n'nap!
Man Two: LOLZ TRU!
Boys who enjoy yaoi (a genre in Japan that contains sexual and/or romantic relations between two men); literally translates to "rotten boy"; corresponding female : fujoshi