look up any word, like cleveland steamer:
 
1.
The term Dumm-yatt is frequently used in Scotland . It is the Scottish equivalent of Mong , Mongo , Dumb ass . It is used to describe someone stupid. Dumm-yatt can also be used to describe someone who fails at life.
Example 1

Person 1 : “aww damn I just dropped my hot dog!”
Person2: “you're sucha Dumm-yatt!”

Example 2

Person1 : “ I failed my math test”

Person2 “what score did you get?

Person1 “ three percent”

Person2 “omg you Dumm-yatt!”
by psychocandypsycho November 16, 2011