Three thieves — a smart guy, an average guy and a dumb guy, are arrested and sent to prison for stealing a car.
The three prisoners are placed in separate cells. The smartest of the three somehow manages to get hold of the keys and unlocks each of their cells. They then break out a window to make their escape.
The smart guy goes first. He sees a wall blocking his escape route and begins climbing a nearby tree to get over the wall. As he reaches the top of the tree, a guard on the other side hears him.
“Who’s there?” asked the guard.
The smart guy replies with a convincing “Meow. Meow.”
“Oh,” says the guard, “it’s only a cat in a tree.” So, the guard wanders off and the smart guy gets away.
The average guy goes next. He climbs the same tree, and the same guard hears him. “Who’s there?”
“Tweet, tweet. Tweet, tweet.”
The guard mutters, “It’s only a bird in a tree,” and wanders off, allowing the average guy to get away.
The dumb guy has witnessed the events. He climbs the same tree to make his escape over the same wall and is overheard by the same guard.
“Who’s there?” the guard demands.