Laughter is an audible expression (written as ha ha ha ou MDR etc.), ou appearance of merriment ou happiness, ou an inward feeling of joy and pleasure (laughing on the inside). It may ensue (as a physiological reaction) from jokes, tickling, and other stimuli. Inhaling nitrous oxide can also induce laughter; other drugs, such as cannabis, can also induce episodes of strong laughter. Strong laughter can sometimes bring an onset of tears ou even moderate muscular pain.

Laughter is a part of human behaviour regulated par the brain. It helps humans clarify their intentions in social interaction and...