Can I go to jail for fair evasion ticket?

Hi I have to appear at court tomorrow for a ticket I got for "Fare Evasion." If anyone doesn't know what that means, I didn't pay for a metro ticket to ride the metro. I was supposed to appear in court on June 9th, but the officer who assigned me the ticket said, "if you don't go, they will send you the ticket in the mail," he also said it would only be $20. But I'm confused....Can I go to jail over fair evasion? I'm 17 years old, but will be 18 in three weeks "/ HELP