Melatonin Dick
Someone who has the power to put someone to sleep during sex.
Guy 1: Yah, man, I fucked her so hard she fell asleep last night!
Guy 2: Woah bro, I didn't know you had melatonin dick
Guy 1: Wow.
Guy 2: Woah bro, I didn't know you had melatonin dick
Guy 1: Wow.