Used as an insult to demonstrate authority, hence the "daddy" part. Most likely performed by the giving end after the recieving end is pwned/owned. Also used by Superfly, one of Joe Cartoon's characters.
Billy: Oh yeah! I just scored 15 3 pointers on your punk ass!
John: Dammit, man..
Billy: Who's your daddy?!
Superfly: Hey man, what's up?
Santa: What's up? Heh heh. What's up?
Superfly: You know who your daddy is? It's me, yeah! I'm your daddy! Do you know how come I'm your daddy? 'Cuz I did this to your momma! Yeah, YOUR momma! Call me Superfly! Your momma!
when ur about to pick up some slut in a club but b4 u bang her u wanna make sure ur not gonna get shot (by her pimp OR if shes in the mafia, actually her daddy)
playa: hey girl come over here
slut: okay, come to my room play: wait- who's your daddy?
Something to tell a hooker in the throes of passion while slapping her ass, or your missus which would either result in increasingly intense fornication or your status changing to single.
#The more the daddy issues, the more useful the phrase.
'Who's your daddy?' said Dr. Long as he slapped Nursie on the buttocks.
'You are' says Nursie (being a pornstar with issues and all)
'Who's your daddy?' says Fred.
'He died last month asshole' Sarah says as she slams the door on her way out.