The cop said something like, "I'll be scraping your head up off the ground with a shovel and mopping up afterwards!."
I was pretty embarrassed as there were several packed cafes on the sidewalk and he was loud. Taught me a lesson I shouldn't have had to be taught. He actually softened after and told me he was partly putting on a show for the female trainee he had, but only partly. He was just doing his job and just maybe he'd had to scrape someone's head up off the road at some stage you know? PTS may have been playing a role in his reaction.
It's bonkers that people don't wear helmets up there, here it's the law of the land. Weirdly, when I go to Thailand I hire a motorbike to get around and my girl gets on the back. Only the driver needs a helmet though, and the helmets they issue are little more than an ice cream tub with a string to hold it on. Few wear them though, so I chose not to and...got caught. Tried to bribe the cop and he almost went for it then got more angry so I decided to go pay the expiation fee, the equivalent of about $12 AUD, rather than end up in a Thai prison. Lol. It was a fun experience.