A rhetorical question, generally in the form of an insulting chant, accompanied by finger-pointing; meant as abuse to a single person or team performing in front of a crowd, by indicating that they are unknown and insignificant.

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.

The horrible moment when you realise that you have accidentally done something very slightly wrong which has very bad (usually embarassing) implications for you. This is typically the moment of realisation that you just sent a dirty text message to a close member of family, typically your mother, rather than the intended recipient.

One of the band "The Who"'s last songs; also found as the theme song for CSI

a rhetorical phrase that insinuates that the person who is being spoken to is either strange or a moron.

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.

Mall Monkey writer Keith Smith's catch phrase. He says it frequently due to the fact that he despises going to the mall on his own time.

A term used to take away respect from someone. (Questioning their reputation or status)
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

Originating on Cape Cod; a greeting between friends... (or enemies)... based on a line from one of Arnold Schwarzenegger's movies, taken off an internet soundboard used to prank call people w/the governator's voice. Rapidly gaining popularity wherever its original users are in college... from Florida to New England. On one legendary occasion, yours truly got Ahhnold himself to say "who ahh you!?" when the terminator was sited at Gold's Gym on the Cape.
(note: must be said with an Austrian accent)