Should I plead Guilty or Not guilty?

At Dave concert, my friend had to go to the bathroom, we went to the porta potty and the lines were ridiculously long, so my friend told me to follow him over behind a dumpster(told him it was a bad idea) he said to cover his sight so no one could see his business, cop comes from around the corner( my pants are up I'm not urinating) umes I was urinating and gets me in a lock and slams me on the cop car. My friend walked away and did not get a summons like me. He calls me an ***hole doesn't ask for my name, just ask if I have an I.D, I said I don't know If I have it on me(b/c i usually keep it in my car), gos in my pocket and my wallet was in my pocket. He writes 3 summons for urinating, improper behavior, and false info. for saying I didn't have an I.D. I'm not guilty but court cost and time might have to force me to plead guilty. Please give me your opinion on what I should do.