Auto-Fellatio

Autofellatio (noun) - For a man to perform oral sex on himself, putting his penis in his own mouth.

Autofellatio is a yet less-common and more unlikely feat than fisting, and it requires certain inborn anatomical peculiarities – if you ain't got it 'em, you ain't gonna get anywhere. Got a pen? OK, take this down: You will need a short torso, a longish dick, and a very flexible spine.