Sometimes we humans (and some animals too, come to think of it), respond to our environment in a peculiar way.
Upon certain conditions, our body performs “rhythmic, vocalized, expiratory, and involuntary actions” [Britannica 1999]. Fifteen facial muscles contract and there is electrical stimulation of the zygomatic major muscle in particular. Currents of varying intensity, produce a wide range of facial responses. The respiratory system is upset by the epiglottis half-closing, so that air intake occurs in irregular gasps, rather than calm breathes. Under extreme circumstances, the tear ducts are activated, so that while the mouth is opening and closing and there is a struggle for a sufficient amount of oxygen intake, the face becomes moist and often red. Noises often accompany this odd behavior “ranging from controlled snickers, escaped chortles, and spontaneous giggles, to ridiculous cackles, noisy hoots, and up-roarious guffaws.”