Would mainly be used to call someone Stupid. But making them seem stupider than already it’s more passionate and expensive sounding.

Can also add the word head e.g Nombty Head after it to say u have a stupid brain.
( Irish slang)

When you eat dirt for the first time and leave your family to build a shack in the woods

Nombty is a word used to call someone really really stupid in the head but in a sophisticated and Irish way.