look up any word, like tribbing:
 
2.
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.
laughter at a funeral
laughter in a work meeting
by jbastard February 26, 2003
 
1.
You are surrounded by people for a moment of silence when the Giggle Loop begins...

Suddenly out of nowhere this thought comes into your head: the worst thing I could possibly do during a minute's silence is laugh. And as soon as you think that you almost do laugh -- automatic reaction. But you don't, you control yourself, you're fine. Whew.
 
But then you think how terrible it would have been if you laughed out loud in the middle of a minutes silence. And so you nearly do again, only this time it's a bigger laugh. And then you think how awful this bigger laugh would have been. And so you nearly laugh again, only this time it's a very big laugh, it is an enormous laugh. Let this bastard out, and you get whiplash. And suddenly you are in the middle of this completely silent room and your shoulders are going like you are drilling the road. And what do you think of this situation? Oh dear Christ, you think it's funny!
Coupling - Series 1 - Episode 'Sex, Death & Nudity'
by Ross Brazier May 18, 2004
 
3.
A feedback-type mechanism whereas someone who thinks about laughing (and doesn't) continues to think about how funny said laugh would be (while not doing it) over and over until they eventually cave, especially during a prolonged moment of silence.
Steve elicited a giggleloop when he kept himself from laughing at Jane's dead aunt.
by Chico The Chairman June 12, 2007
 
4.
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 ADDING
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
by 4giggles November 13, 2006