very specific way. pigeon laughter, which is often practiced in laughter therapy or laughter yoga, involves laughing without opening your mouth. by keeping your lips sealed, the laughter produces a humming sound, much like the noises a pigeon makes.
it's also been compared to the humming of bees, so if you're still angry at those darn pigeons for dropping poop on you, feel free to call it bees' laughter. 