This is similar to other tricks that have been posted, but the others, so far as i know, no longer work. All you need is a friend who saved some Halloween wands and a Vial of the Sands (I believe the Stone Drake mounts work as well).
Essentially, the mounts that turn you into drakes are effectively "costumes" and you can sometimes overwrite them with other costumes while keeping the mounted effect. A lot of things don't work, because you can't mount with them, but many do work.
Use your drake first. Stay on the ground. Have a party member use a Halloween Skeleton Wand or Random wand on you. Once your transformed, you can fly away in in your new costume. If you used a vial of the sands, your friend can even mount you like a hand-puppet.
Other wands might work, but i Know a few give errors. The random wand will sometimes fail, resulting in a wasted charge. It works for the ghost costume and most likely the pirate and leper gnomes, but will probably fail with the others. If someone has a spare Ninja/Pirate wand lying around those would certainly be worth testing, but Skeleton works 100% and random works part of the time.
Like the infinite non-combat pet exploit, this won't let you get any secret advantage, just look really awesome . . .