I would advise contacting a criminal defense lawyer regarding your case as soon as possible. You don't want a criminal conviction on your record.
Juan Garcia Jr.
Attorney At Law
It is unclear if you are being charged with an infraction or a misdemeanor. In either even an attorney would be a significant help to you. This is certainly not a case that a prosecutor would want to take to trial and they would be willing to deal on.
Be very, very careful about what you do in this case, or you could wind up with a nasty surprise!
I have seen people charged with indecent exposure, Penal Code 314, for urinating in public. This is a misdemeanor that carries lifetime registration as a sex offender. Simply answering the call of nature is not sexually-motivated "weenie wagging," and a person should NEVER plead guilty to indecent exposure in a public urination case.
Los Angeles Municipal Code section 41.47.2 makes it a misdemeanor, punishable by up to six months in jail and a $1,000 fine, to urinate or defacate in public. Public urination is often charged as Penal Code 374.3(a), unlawful dumping of waste in a public place, which is an infraction with a maximum fine of a thousand dollars.
You say there's "no evidence," but the bouncer's testimony is enough to convict you if the jury (or judge, in a non-jury trial) believes him.
If you are charged with a misdemeanor and cannot afford a lawyer, you are entitled to a court-appointed attorney from the public defender's office. If it is an infration, you're on your own.