Darry taught Sodapop and Two-Bit and the rest of the boys acrobatics when he had taken a class at the Y one summer. He figured it would help them out in rumbles. Well, one day Soda and Two-Bit were flipping down sidewalks and walking on their hands. The basically got arrested for being a menace to society and a public nuisance.
"They were doing mid-air flips down a downtown sidewalk, walking on their hands and otherwise disturbing the public and the police. Leave it to those two to pull something like that."
In Chapter 9, the Greasers are getting excited about fighting the Socs and begin doing somersaults and flips off of Darry's front porch on their way to the rumble. Ponyboy mentions that each gang member was able to do acrobats because Darry had taken a course at the Y and taught each of the Greasers what he learned. Darry thought learning acrobats would come in handy during a fight. Pony then comments that Sodapop and Two-Bit were arrested one night for doing flips downtown and walking on their hands. Pony says that the police arrested them for "disturbing the public." This is typical behavior for Sodapop, who is always rowdy. One could imagine seeing Two-Bit and Sodapop yelling, laughing, and causing a disturbance as they do flips and somersaults on the sidewalks. The Greasers already have a bad reputation throughout the community and their behavior would give the police a good reason to throw them in jail.