are you a benny tied to a tree?
If you ask someone whether they are a benny tied to a tree, they will generally reply "no". This will give you the opportunity to run away, screaming at the top of your voice, "BENNY ON THE LOOSE!"
written by Sl*m Jim, approved by Log

And, if a potential victim is wise to this and says 'yes', you scream 'Fucking Benny!!'
written by Ja*es*Harve*, disapproved by Phil

Amen! Interestingly, 'Benny' is another geo-specific term and unheard of by some. Bennies! I remember a slight variation to the question, involving a benny in a cage.
written by Ia* R, disapproved by Susan

We used to do that exact same thing, excpet it was bummer not benny.

Another favourite variant was to lean over and whisper some mumbled gibberish in someone's ear and then look at them meaningfully. When they said "What?" or "Pardon?" you would repeated this tactic, perhaps throwing in their name to make it appear that you were saying proper words.
Do this a few times until they are fairly annoyed, and then shout "I SAID, bummers are deaf!"
written by He* Phil*ips, disapproved by Log