A term coined by NBC's 30 Rock. It's when you shake your index finger at someone to make a point to whatever you're saying. First used in a season 5 episode called "Plan B" by Jack Donaghy (Alec Baldwin's character).
Liz - "You're looking out for us, right? Pounding on desks and doing whatever this called." (she's shaking her index finger)
To ditch an event or school
"Hey Damo,what did you do on Tuesday?"
"I fucken wagged school because i'm a real Aussie cunt"
"Hey maybe you shouldn't wag school"
"HEY SHUT YOUR BLOODY MOUTH BEFORE I MAKE YOU.Wagging is what a true aussie does,unlike you Clancy"
"Wagging is what adipshit bogan does because he hates school,and i'm a dipshit bogan that hates school"