Never speak ill of the monarchy, never step on money
Don't criticize, joke about, or disrespect the Thai royal family, in person or online — it's a real criminal offense (lèse-majesté) carrying years in prison, not just bad manners. Never step on or deface Thai currency either, since every note and coin bears the King's image.
Avoid any critical, joking, or disparaging comment about the King, Queen, or royal family, in conversation, online, or on social media, including posts made before you arrive in the country. This isn’t a soft cultural preference, it’s enforceable Thai law, and it’s been applied to visitors as well as residents.
Never let a banknote or coin touch the ground and get stepped on, and don’t deliberately damage or deface currency, both read as a direct insult to the King’s image printed on it. Hand money over and receive it with care, using both hands for anything formal is a safe, respectful default.
Stand for the royal anthem if you’re in a cinema before a film starts, or when the national/royal anthem plays in a public space, standing is the expected response, not optional.
Don’t photograph yourself in a disrespectful pose with a royal image or statue — treat portraits and monuments of the King with the same seriousness as the person himself.
Why it matters
Thailand's lèse-majesté law (Section 112 of the Criminal Code) makes defaming, insulting, or threatening the King, Queen, heir apparent, or regent a criminal offense, punishable by 3 to 15 years in prison per offense. Enforcement has been strict and has included social media posts, and reportedly cases where posts made outside Thailand before a visitor even entered the country were prosecuted. This is the rare entry on this site where the consequence is legal, not social. Currency carries the same weight for a related reason: since it bears the King's image, stepping on it (feet are considered the lowest, least respectful part of the body) or damaging it is taken as a direct insult, not simple carelessness.