Abuse is aimed at two groups:
1) An unknown competitor, whose relative anonymity is highlighted even further.
2) Paradoxically, a well-known competitor whose high credibility and status is undermined in an act of defiance by pretending to regard the competitor as unknown or insignificant.
Abuse is aimed in two ways:
1) When the competitor is announced.
2) When the competitor is performing badly.
The phrase is often used in sport, particularly at football matches in the UK.
1) Liverpool (big football club) v Grimsby (small football club):
Announcer : "On to the pitch comes...Grimsby"
Liverpool fans : "Who are ya?! Who are ya?! Who are ya?!..."
2) Leyton Orient (small football club) v Chelsea (big football club)
The Chelsea player, Didier Drogba, misses a clear chance of scoring a goal and falls over badly, clutching his knee in agony.
Leyton Orient fans : "Who are ya?! Who are ya?! Who are ya?!..."
the person being spoken to with usualy reply with their full name but you're never actually looking for an answer, hence it being rhetorical.
This term is not used lightly, and if its thrown around, someones sure to get knocked the FUCK out.
Variation: Who do you think you are, who is you
guy2: Who is me? who the FUCK is you?
(note: must be said with an Austrian accent)
-"I'm Detective John Kimble!"
-"WHO ARE YOU!?!?"
-"I AM QUAID!!!"