So there's these blue people...

not unlike Smurfs, called Trids. The Trids are very special in that they only live in once place-- on an island in the middle of a lake. The island is connected to the mainland via a bridge and the Trids have to cross this bridge to gather food for the Trid village.

Unfortunately, there's a large Troll that lives under the bridge that likes to kick unsuspecting Trids into the water when they come by. Oh did I mention that Trids melt when they come into contact with water? Anyway, these Trids have tried various methods of dealing with the Troll (usually via sending more Trids across than the Troll can kick) until one day they just can't do it anymore. There aren't enough Trids left to swarm the Troll. Despair sets in. Luckily, a wandering Rabbi finds his way to the Trid village and is greeted warmly by the Trid chief.

"Rabbi, Rabbi, please help us." says the Chief Trid
"What can I do for your people?" responds the Rabbi.
"Please, would you gather the food for my people because we can no longer deal with the Troll in our usual way as our numbers have been decimated." Chief Trid pleads
"Sure" the Rabbi responds.

So, the Rabbi spends the next few days making trips across the bridge to gather food for the Trid village, having not once been bothered by the Troll.

Finally, one day, tired of making trips across the bridge and eager to find a solution to the Trids Troll problem, the Rabbi stops to talk to the Troll.

"Troll," says the Rabbi, "I have made dozens of trips across this bridge to gather food for the Trids, and not once have you tried to kick me. Why is that?"

The Troll replies smugly, "Oh silly Rabbi, kicks are for Trids."