To fail at an amazingly easy task, or (in contrast) to succeed in an amazingly difficult one. Mostly refers to sports.
Generally said whilst tapping one's nose or raising arms at a 90degree angle triumphantly.
1 - Two blokes are playing billiards. Bloke 1 has the 8 ball a centimetre from the top right pocket.
Bloke 1: You might as well cough up that $10 now, mate.
*Bloke 1 buggers up the shot*
Bloke 1: I can't believe I did that.
Bloke 2: That's a Peter Collis *taps nose* if I ever saw one.
2 - Two blokes are playing golf.
Bloke 1: Oh man, I'm getting slaughtered here. I hate this hole.
*Bloke 1 hits a hole in one*
Bloke 1: HA! PETER COLLIS! *raises arms triumphantly*