So, I was bored today and started coming up with some mean things to do to other people as a mage.
One would be, get into a group for VOA, and then run up to the portal, and toss up a Stonard/Silvermoon City port right infront of the WG portal.
Another fun thing to do, where they have all the portals to major cities in Dalaran, they have have a few empty slots. Toss up a portal in the first slot next to the one to Org. You'll see people run up to it and just stand there. They'll then wonder if the portals are broken or something. I did this and two people actually asked in trade chat if the portals were broken or something.
Another fun thing to do is during any boss fight where there is a huge AOE spell getting ready to happen. Buff someone with AMP Magic. Teehee.
Anyone else got anything?
EDIT: The thing about the portals in Dalaran is for the Horde side. I forget what the Alliance side looks like. Don't know if there are any empty slots there or not.