So I tried a few searches, nothing related to this. I found this by myself, and wasn't sure if it belonged in the exploits forum or this one, but it didn't matter since I couldn't post in the exploit one yet anwyay.
Basically you need any flying mount and to be in northrend or outland.
Steps:
1. Use your flying mount and go absolutely anywhere outside of shattrath or dalaran.
2. Press escape on your keyboard then logout.
3. Right click your mount buff.
You'll be floating in the air like this:
(need 3 posts to be able to post links to image -_-)
Obviously you can only do it for 18 seconds or so but it's fun to do and makes a lot of people ask how you're floating. Can perform various emotes such as /dance, /sleep, /sit. Works at any height but make sure you have something like slow fall, divine shield, levitate or a noggenfogger elixer if you're going really high.