Depth charge

n.

Heard in Limerick and Tipperary

A particularly heavy bowel movement - the sort of one that would sink a world war 2 U-boat without even trying.

In use

I was creaking at the gunwhales until I dropped that depth charge in your new jacks, I think it cracked the bowl.

Posh English

My constitution was groaning under great strain until I deposited that colossal movement into your new water closet, which I fancy fractured the porcelain.

Same phrase, other counties