To be "cooked in the head." Probably comes from "fried" or "brain fried." Imagine how someone would act if their brain was at least partially cooked. Could mean under the influence of drugs/alcohol or someone acting crazy or out of the ordinary.
Dude, did you see that guy in McDonalds last night drunk and singing Duran Duran using an Ice Cream cone? He was totally cookered!
by UrbanDictionarianGod November 05, 2015