Definitions by Michael B Hawke

cock my bum 

An expression of abject surprise; the user is so shocked that he/she has transcended the boundary between noun and verb and utilsed the word 'cock' as the latter.

Prima: Dude, Elly just pissed all over your cat while it was sleeping.

Secunda: Cock my bum.

cock my bum by Michael B Hawke October 6, 2009