It is illegal to step on any piece of the nation’s currency.
Thailand takes their king pretty seriously, and it’s against the law to insult him. Since the king’s picture is on the Thai currency, and the foot is considered particularly dirty, stepping on a piece of currently is equated to a direct insult of the king. This action could land you a beating, or jail.
Disposing of chewed bubblegum in public is a $600 fine.
Officers of the Bangkok Metropolitan Authority (BMA) frequently enforce this aspect of the public littering law. The fine is up to 2000 Baht.
It is illegal to drive a car or motorcycle without a shirt on.
Rumor has it that the penalty ranges from a slap on the wrist to a ticket for a few hundred baht. Thankfully the exchange rate is favorable and this is around $10 US.
It is illegal to not wear underwear in public.
You know that old adage about making sure you leave the house with clean underwear? Well… it would appear that dirty underwear is better than no underwear at all!