The suspect excuse that a mate gives you for not going somewhere, or doing something. Named because the real reason for him not going somewhere or doing something is that he is a wimp, and therefore has no penis.
Person 1: 'Have you herd why Alex isn't coming today?'
Person 2: 'No, do tell'
Person 1: 'He's ill, and last night he was "throwing up all through the night"'
Person 2: ' A cockless excuse if i ever herd one'