Milkhead originated in Philadelphia, 2004AD. The actual phenomenon was born 1990 AD. It is used for specific losers (lo-ser) who can be described in no other way except for Milkhead.
It is commonly used for girls who have no idea what they are talking about.
A small piece of information. Derived from the word ken, used often in the scottish language and is synonymous with knowledge.
Person 1: "Hey I don't get this shit. How do you solve this problem?"
Person 2: "I got that one. Give me some kenlets on this assignment and I'll help you w/ that one."