If I don't show up to court, what happens?

That really depends on your status, and what you were supposed to be there for. If you already posted bail, it could mean you are just found guilty, your bail is forfeited, and that's the end of it. If you were to be there for a trial, the judge will probably will issue a warrant, and/or suspended your driver’s license.  Then we will go looking for you to arrest. It's not a smart thing to skip out on appearances, because when warrants are issued, they hang around for years, waiting for you.