... And get your vocal chords into it
                                
                                
                                    (Newser) -
                                    When it comes to laughs, the bigger the better, at least if you want it to spread. In one of those science-confirms-the-obvious studies, researchers found that open-mouth laughs in which people use their vocal chords in "vowel-like bursts" are the most contagious,  LiveScience  reports. And the longer they last,...