Thais believe strongly in the concept of saving face, ie avoiding confrontation and endeavouring not to embarrass themselves or other people (except when it's sà·nùk to do so). The ideal face-saver doesn't bring up negative topics in conversation, doesn't express firm convictions or opinions and doesn't claim to have an expertise. Agreement and harmony are considered to be the most important social graces.
While Westerners might think of heated discussion as social sport, Thais regard any instance where voices are raised as rude and potentially volatile. Losing your temper causes a loss of face for everyone, and Thais who have been crossed may react in extreme ways. Minor embarrassments, such as tripping or falling, might elicit giggles from a crowd of Thais. In this case they aren't taking delight in your mishap, but helping you save face by laughing it off.