Definitions by Kerplunck!

your mother's clam 

a phrase used to describe the genitals of the person in question's mother, often used interchangeably with "your mother" after something is said to achieve insult or "burn"

"I can't take this any longer"

Your mother's clam can't take this any longer!"

your mother's clam by Kerplunck! February 11, 2015