A 'skerrat' is an ever-more-popular term for a person who is generally insufferable to the point of enraging any reasonable person they meet. Diagnostic criteria dictate that the following two items must be true for someone to qualify as a skerrat:

1) You fucking hate them.
2) You'd smile (or laugh/cheer/wank) if they died.

'Skerrat' derives from a chavvy dialect's mispronunciation of the modern word "scrote", which itself is a derivative of "scrotum", which is again slang for the technical term, "ballsack", or even more properly, "bollocks".
Person one: "You're such a Skerrat."
Person two: "I'm a scrat?"
Person one: "No, 'Skerrat'. You're such a Skerrat."
Person two: "No idea what you're talking about; I must visit Urban Dictionary to find out what you mean."
by Endangered_Dodo February 23, 2009
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