"Please stop putting out ads for aliens to come and teach you our secrets of advanced dental hygeine and folk-dancing. It is embarassing to you and to us. We have gone back in time and erased the tails of your entire species as a warning. Don't push it."
Yay! My ad worked! Hope you didn't, you know, need those tails, everyone.
I'm just glad it worked. All I ever got from the werewolves was a cease and desist letter.