In the 22 years that The Late Show With David Letterman was on the air, the titular host met and interviewed countless celebrities. His most interesting guests, however, were the ones he profiled in a segment called "Stupid Human Tricks." These people may not have been famous, but each of them had a unique trick or talent. Here, Annabella Almeidia shows off her ability to chew gum, spit it out, and suck it back in. Sure, it sounds disgusting, but the audience eats it up!