there is no fear of mall security. The worst thing that could happen is that they will ask you to leave or they will call the police...
Wrong. Certain malls, like Mall of America in MN have as security only licensed police officers so any security officer has the power to arrest and detain. Other malls have one police officer on duty at all times so they can arrest on the spot.
Most will ask that you cease and desist and at the same time spread the word via radio describing you and warning others to watch for you. If you just move to a different part of the mall, you can be arrested, taken to the security office and held for transportation to a jail for trespassing or creating a disturbance.
Depending on the jurisdiction that you live in, the results could be a fine up to several hundred dollars ($500 where I live) plus a couple of days in jail if you really urinate off the judge.