Did you do that yourself?
An innocent question that is not a compliment. Asked with a smile about a haircut or a home job.
Lovely shelf. Did ye do dat yerself?

Shall I translate it into posh English for you, head?
Hello, you marvellous creature. Here it is in posh English.
What a charming shelf. Was it, perchance, entirely your own handiwork?
Questions
What does did you do that yourself mean in Ireland?
An innocent question that is not a compliment. Asked with a smile about a haircut or a home job.
How do you use did you do that yourself in a sentence?
“Lovely shelf. Did ye do dat yerself?”
Updated
On the list: Irish slang phrases