When someone is Lurking in a state of perversion to make people think that they are not here/there (Mostly IRC) when infact they are drooling at their screens.
Then come out from no where and say the most random obscene phrase imanginable such as: "ngr" masking nigger, or "cunt".
People that DO A KERRIE are often on peoples dicks, and they cant say shit without them, the odd ocasion they are not DOING A KERRIE they are on someones dick trying to slate someone and still get merked.
Most Commonly found in teenage girls
and middle-aged men.
n00b1: "Hey where's n00b3"?!?
n00b2: "Oh he's here somewhere, just DOING A KERRIE!"