Taking the definition from jbastard on Feb 26 ... Uncontrollable laughter, often snowballing beyond one's control and leading to some humiliation. Best observed when you are the only one laughing and no one around you knows why.
And people around you start laughing even tho they don't know what you are laughing about and then you really can't stop and they can't stop and when it all finally rolls to a stop with ribs splitting and face aching you tell them what started it for you and they are all totally bewildered. It's a viral giggle loop.
Eating lunch outside with friends and the wind makes Joe's hair swirl around like a dead squirrel rolling around in a Chicago wind, but by the time you stop laughing there is no way to explain it.
Nikki started a giggle loop and I couldn't stop busting a gut til my face fell off - hair and squirrels thing