To pass the time while in jail this guy finds, and trains, an ant. The usual tricks, pushing toothpicks, fetching tiny bits of paper, you know. After a while, the ant gets pretty good, and the guy starts having dreams of life after prison.
The big day finally comes, and the guy is turned loose. He takes his ant, proudly walks out of the prison gates, and into the first bar he sees. He figures bartenders know a lot about local goings-on, and he's looking to score big with his ant.
He walks in and sits at the bar, carefully placing his ant in front of him. He calls the bartender over.
"See this ant?" says the guy.
The bartender looks at the ant, then squashes it with his thumb.
"Pesky little critters, aren't they?"