To engage in an uncontrollable series of of shrill laughs, which are often uncomfortable to the ear. Sometimes abbreviated to "CF."
My boss's friend just called him for a 20 minutes cacklefest. I had to close the door to his office to dull my headache.
(n) The laughter of a small group of friends at something really stupid and funny, such as: a Youtube video, video game, movie, TV show, etc.
It was a real cacklefest after Niko Bellic did several backflips after crashing his motorcycle into the subway car.