Suggest put an advertisement on during The Simpsons advising all civil aircraft have now been fitted with laser-seeking guided devices which will fly back down the beam and cover the holder and 10 metres around them with the entire contents of the lavatory tank. Some nice CG rendered visuals for added persuasiveness, should slow them down a bit.
After that, if you can catch 'em, you should be allowed to kill 'em.
VHCU