Duuh is a typo of "Duh".
Often like "Lool" this is caused by fat finger syndrome (FFS)
Either that or you're just too stupid to type out "Duh"
"Duuh" is also the sound a walrus makes (Or at least we imagine so)
Example 1:
Sarah: OMFG YOU SAID YOU DIDN'T HAVE A MO PED. I TOLD YOU THAT YOU LIE! LIES! ALL OF IT! AND IN ADDITION TO THAT, IT'S SPARKLY BLUE!
Morgan: HAHAHAHA, DUUH
Example 2:
Walrus: DUUH!
14👍 7👎
saa duuh
person A: Hwy what up
person B: saa duuh
person A: what?
person B: saa saa duuh
Person A: ohhhhh