Your friends, coworkers, neighbors, family, even your bitter mailman,pick up on your fake laughingtwo thirdsof the time according to newser.com . According to nerds at UCLA (who are ruining my attempts to be polite) we distinguish fake laughter from the real deal mostly by listening to speed and breathing patterns. Check out what they sound like. But smarty pants Dr. Sanjay Gupta thinks you should laugh (or fake laugh) anyway.
Plus sometimes your fake laughing turns into other people real laughing, and I can't think of a cooler thing to do for a stranger.