Parodied in YTMND, "No Wai!" is a sarcastic expression of disbelief in something that is obvious.
Commonly associated as a response by the O RLY owl (who says "O RLY?") after someone says "YA RLY," conversations end in a mock tone.
(Cloudy weather outside)
"Dude! It's going to rain today."
"O RLY?"
"YA RLY"
"NO WAI!"
82👍 33👎