Dirty baist
A generic insult. Look at that dirty baist. He's a dirty baist. Beast, said the Ulster way.
Heard in Antrim, Down, Derry and Tyrone
Look at that dirty baist / he's a dirty baist

Shall I translate it into posh English for you, mucker?
How do you do? Here it is in posh English.
Observe that thoroughly disagreeable creature. He is a thoroughly disagreeable creature.
Questions
What does dirty baist mean in Ireland?
A generic insult. Look at that dirty baist. He's a dirty baist. Beast, said the Ulster way.
Where in Ireland do people say dirty baist?
People say dirty baist in Antrim, Down, Derry and Tyrone.
How do you use dirty baist in a sentence?
“Look at that dirty baist / he's a dirty baist”
Updated
On the list: Irish slang words
Same phrase, other counties
- Down (not in the dictionary)
- Derry (not in the dictionary)
- Tyrone (not in the dictionary)