Laugh is what depressed kids don't do. They like to cut themselves and be happy that way, but they never laugh. Laughing is the act of saying "Haha" while breathing at the same time to produce words from the vocal chords of the throat.
It's what you do if you watch someone fall off a cliff. It's also what you do if you see something stupid on TV that you think is funny. Some people laugh at the wrong time, such as at a funeral, a church, or at a class clown in which their teacher is old and doesn't like people who laugh.
Laughing Syndrome Edit
Laughing is a symptom of a deadly and severe common cold, in which is considered a pandemic because so many people get it. If you start laughing at any time, please stop and call your doctor, because you may have Laughing Syndrome.