One of the many synonyms for 'twat'. After a while, the regular insult exchange evolved into:
Kid A: You're an eef!
Kid B: Eef what?
Kids A+B (singing): Eef I was a rich man...
They would then continue to sing any of the rest of the words if they could a) remember them, and b} be bothered.
written by Ma*t F*sh*m, approved by Log