ive only tested this on an alliance character, and you have to be at least high enough lvl to be able to beat the 2 revelers down. heres the story. i went to splintertree post in ashenvale to mess with the horde a bit. when i was in the inn i attacked the revelers, but before i killed one, i did /kiss to it. i ended up getting the mistletoe, and when it died, it turned from an orc female in a santa outfit to a human female in some plain looking stuff. so i killed the other one too and it turned into one as well. heres a SS of it.
this isnt exactly an exploit more over a funny bug. have fun with it, lol.