When a person purses their lips in disagreement or disapointment. Often accompanied by Stink Eye
She looked at me with obvious disaproval as I let fly with a trouser cloud and gave me the 'Cat's Bum'
by Odi Cologne February 03, 2004
A person with a face like a cat's bum; a sour-faced person.
Don't worry about Sheila's scornful response, she's just a catsbum.
by Freddie Frackshat July 01, 2010