It's an instinct that some people have when their mouths are subjected to shock like that. I saw it several times over the last 2 days here in Albuquerque, NM. This past weekend was the Annual Fiery Foods show at Sandia Casino and Resort, and let me tell you when people took their first bites of the really, really hot stuff, they initially start coughing and then unknowingly take another bite. By that point it's pretty much all over and then the beads of sweat start to come down. It's quite funny to see in person, but I would never try the really hot stuff, jsut give good 'ole New Mexican green and read chili.
That clip of Rob Stone, by the way was at New Mexico State down in Las Cruces, NM. Very close to Hatch, NM (were most, if not all NM's green chili comes from).
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Pat Patterson