Hello again folks!
I had the utmost disgust to discover this very annoying exploit/bug first hand (as the one being kidnapped!) Me and my mates were playing along in Icecrown as we had a guild vs guild world-PvP war. After we were done with it, I mounted up on my Loaned Gryphon mount (very bugged mount that you can get for free from K3 - Storm Peaks) and my friends started laughing at me on ventrilo when they saw my lousy 60% free mount!
They soon started mocking me and flied around me with their 310% mounts and we were having a laugh on ventrilo.
Suddenly my friend noticed that he can right click on my mount for some reason just like it was a vehicle and he clicked it.
I noticed ALL my toolbars went grey and I couldn't move at all
BUT MY FRIEND COULD MOVE AROUND WITH MY MOUNT AS THE PASSANGER!!
Anything I tried to cast or do (including logout, AFK log out, queue for BG, get queued for BG by others [you can get queued but cannot enter the bg as it pops], auto-unstuck) gave me a message saying "You cannot do that while being charmed" or so.
All you gotta do is ask someone to get the Loaned Gryphon mount from K3, invite him to a party and jump on the mount by right clicking it. You can then do whatever you want with the mount, fly around or just AFK or even disconnect from the servers (without logging out, use ALT + F4) and the guy who you just kidnapped CANNOT get out of the mount by ANY means! If the guy who you kidnapped disconnects himself and relogs, he will still be locked inside the mount as long as you don't jump off of it.
Edit: Oh and by the way, you can also get your kidnapped person repair costs by flying around to some mobs, and the OWNER of the mount will take the damage! You just have to stand there and let him die and he cannot do anything to stop it!
I tried EVERY SINGLE MEANS to get out of the mount for about 2h of getting flied around by my idiot friend!
Have fun using this before it gets fixed
Here's a screenshot of me being locked inside the mount and having all my bars greyed out and not being able to do ANYTHING at all!
http://img2.imageshack.us/img2/3581/gryphonlol.png
Edit: Here's a second screenshot where you can actually see the gnome female warrior who's in control of MY CHARACTER AND MOUNT! (Her piggy tails are visible through my night elf's body!)
http://img151.imageshack.us/img151/3447/gryphonlol2.png