It's a stupid meme. Public urination, like actually taking a piss in public while no one is around you, is likely going to be a ticket for disorderly conduct if a specific charge for it doesn't exist. You won't get an indecent exposure charge unless you're purposely exposing yourself to others, it requires intent. Sometimes flashers will use the excuse of urinating for their intentional exposure or will lie that their indecent exposure charge was due to public urination and not because they were really masturbating in plain view. There probably have been prosecutors that have tried to slap an indecent exposure charge on an innocent public urinater but like everyone else says, they can't find any proof of it actually sticking.