What happens to Gloria because she laughs so hard at the story of Otis's arrest?

Opal learns about Otis’s arrest from Otis himself, on her first day of work at Gertrude’s Pets. On this day, Opal and her dog Winn-Dixie chance on Otis playing his guitar to the pets. Otis explains to Opal that he sometimes likes to make music to the caged animals because he understands what it feels like to be locked up all of the time; he once was a jailbird.
Many days after this incident, Opal decides to tell her friend, Gloria Dump, about what Otis told her, that he had once been in jail. Gloria advises Opal to learn to “not always judge others by the things that they have done, rather by their present deeds”.
One day, Otis divulges to Opal the real reason why he was jailed. He says that he had been playing music on the streets when he was accosted by a group of policemen. The policemen wanted him to stop playing his guitar along the streets. However, he refused to comply and when they tried to handcuff him, he became violent and hit at one of the policemen. For this violent act, Otis was arrested.
In Chapter 20 of the story, Opal tells Gloria the reason why Otis went to prison. When Gloria hears the story, “she laughs so hard that she has to grab hold of her false teeth so that they do not fall out of her mouth”. Gloria laughs because the story given to her by Opal does not present Otis as a tough, dangerous criminal who belongs behind bars. In fact, it is hilarious that Otis really was jailed just for his passion for music. Clearly, Otis had not wanted to hurt any of the policemen. He had just wanted to play music for other people’s enjoyment. Gloria laughs at the irony of it all.