An expression used to connote:
1. the act of something stupid,
2. something really lame,
3. something obvious.
The 3nd meaning is used closely more like a synonym for "Duh!"
(Person 1) I just fell from my bike, after attempting to make a 360 on bike
(Person 2) Urrrrr, stupid.
Are those shoes with little lights?
Urrrr, how lame! That is so yesterday.
*With emphasis on the rrrrr, but not to much as in roawr, kind of like DUH*
(Person 1) Are you coming for the weekend? You said you were... o_0
(Person 2) Urrrrr!
*Again, this time like DUH!*