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1. An affectionate abbreviation of the name of the hertfordshire town Berkhamsted, used by the working class and middle class residents alike (see berkhamsted).

2. A word used to describe someone as racist, xenophobic, and totally anaware of any world outside of Berkhamsted. Specifically coined at the University of Sussex, in the mid-2000's. Particularly used by drama students.
1. "Come on Berko! Come on Berko! COME ON BERKO!" - Commonly heard on saturday afternoons at the Lilywhite 'stadium'.
"Uh, yah! I, like, go to Berko girls' school"

2. -"Are there gunna be any darkies there?"
-"God, you're so berko"
by Kyle Ross Richardson May 18, 2007
To lose the plot - usually with a lot of cursing, swearing and wild gesticulating.
"Bob is going completely berko over that mistake!"
"His team lost the match and he just went berko!"
"If I don't get served next I'm going to go berko!"
by Schlub September 30, 2007
When someone is crazy, or insane. Off the deep end. Berserk. A nutter.
"Watch out for Ethan, he's totally berko!"
by Colin Kelly March 25, 2006
Too 'lose the plot' as to say. Yell abuse etc...

Mentally or emotionally upset; deranged: berko with grief.
One that is violent, upset, or unrestrained.
A situation has not worked out as you hoped (you go 'berko')
by Neri August 07, 2006