A phrase overused by the punch rock group, "Green Day". It's used in their song "Know your enemy". It is a nonsensical utterance used to fill in the last two notes of the chords of their chorus.
Do you know the enemy?
Do you know your enemy?
Well, gotta know the enemy, wahey!
Common phrase for-- This is not a common phrase. "Wahey" is-- is... pointless. Not evenpeople who have fits of joy who say "Wahey!". In fact, there is only one person who says "Wahey!" but his name shall not be revealed, or he will have to kill you.
Person A: Hey, check it out! I found 400dollars on the ground!
Wahey Wielder: Wahey!!
Person A: Uh-- ok?
W.W.: Wahey!! Moop! Fiibit! Fibit!
Person A: Goop!