http://cclu.blogspot.com/2005/06/wh...-daddy-now.html

http://www.answers.com/main/ntquery?s=who's%20your%20daddy%3F&gwp=16

A slang term meaning "I control you", which is often used in prison and by members of the underworld. The expression, which can be traced back to the mid 1800's, has two sets of connotations: "I am looking after you" or "you are defenseless". The former usage may be derived from the term "sugar daddy," and often has sexually suggestive undertones; the latter usage may allude to parental dominance and authority.

Today, the expression "who's your daddy" is commonly used as an assertion of domination or sexual control in return for payment or protection. It is also sometimes used literally, as an insult questioning a person's parentage.