Oskar's glass-shattering trick at the Stadt-Theater has given him a taste for the performing arts. He recalls a time when he was young that his whole family went to see a play version of (what better) Tom Thumb—the story of a little person who's no bigger than a human thumb.
Oskar identifies with the main character, who's able to do great things despite his tiny size.
Later, Oskar and his family go to a concert called Opera-in-the-Woods. But Oskar's sick and tired of being on the sidelines. He wants to be the main performer.
So during one of the performances, he sings and shatters all of the stage lights, plunging everything into darkness. He's learned how to silently shatter glass with his voice. Kind of like those frequencies that dogs can hear and you can't.
Years later, Oskar goes to the circus with his family. While at the circus, he runs into another little person. The man's name is Bebra and he's one of the circus's head clowns.
Oskar admires Bebra's performances and respects him as a little person who gets to be center stage at the circus.
Oskar gives Bebra a little sample of his glass-shattering voice, and Bebra applauds. He asks Oskar to run away with them and join the traveling circus.
Oskar's too afraid, though, and declines their offer. He says he'd prefer to do his tricks in secret.
At this point, Bebra gives some advice that Oskar will never forget.
He tells Oskar that the world's about to become a difficult place for little people like them, and the only way to make it in this world is to manipulate people so that they won't manipulate you.
Oskar takes the advice. Before leaving, Bebra kisses Oskar on the forehead.
We're now into the mid-1930s. The Nazi Party is gathering steam in Germany, and Oskar can see signs of this in Danzig. The party starts to hold regular rallies and parades.
There are speeches, marching bands—the whole shebang.
This is exactly what Bebra said would happen. But Oskar isn't going to just sit on the sidelines.
One day, during a Nazi Rally, Oskar squeezes beneath the grandstand.
He waits until the Nazi marching band walks by, then starts playing his drum to a different rhythm. They're playing military marches, but he plays pop music.
Suddenly, members of the band can't resist. They start playing along to the pop music and the entire crowd breaks out into a communal dance. People pair up with one another.
The only person who doesn't have a partner is a guy named Lobsack, the Nazi leader who's directing the rally. He has to dance alone.
Afterwards, the Nazi guards start searching through the grandstands, looking for the person who sabotaged the band.
Oskar's so small that they can't find him.
Oskar then claims that he'd pull this trick many times in the next few years without ever being caught. As his mentor Bebra would say, you have to be the one doing the manipulating, or else others will do it for you.