→Subscribe for new videos every day! http://bit.ly/todayifoundoutsubscribe →Why Do Superheroes Wear Their Underwear on the Outside?: http://bit.ly/1Ow7J0K Never run out of things to say at the water cooler with TodayIFoundOut! Brand new videos 7 days a week! More from Today I Found Out: Why Some Countries Drive on the Right and Some on the Left http://bit.ly/1MpMkZ1 The Surprisingly Short History of the Pony Express http://bit.ly/1forgUD Why Superheroes Wear Their Underwear On The Outside http://bit.ly/1Ow7J0K In this video: In medical terms, a hiccup can be called a hiccough, a synchronous diaphragmatic flutter, or singlutus. Hiccups are classified into three categories: normal, protracted or persistent, and intractable. Protracted are those hiccups that last over 48 hours, but not more than one month. Intractable hiccups continue for more than one month. If hiccups occur for less than 48 hours, they are considered ‘normal’. Want the text version? http://www.todayifoundout.com/index.php/2012/05/what-causes-hiccups/ Resources/Further Reading: http://www.scientificamerican.com/article.cfm?id=what-causes-hiccups http://www.medicalnewstoday.com/articles/181573.php http://www.umm.edu/pediatrics/pdf/newsletter_win09.pdf http://today.msnbc.msn.com/id/17643118#.T57mU8V2OS0 http://facts-and-factoids.blogspot.com/2010/04/worlds-longest-attack-of-hiccups.html http://www.etymonline.com/index.php?allowed_in_frame=0&search=hiccup&searchmode=none http://en.wikipedia.org/wiki/File:Respiratory_system.svg Image Credit (Thank you) http://cdn.spectator.co.uk/wp-content/uploads/2013/03/PA-9551881.jpg http://upload.wikimedia.org/wikipedia/commons/e/ef/University_of_Maryland,_McKeldin_Library_(5063343578).jpg http://callforphotos.vvmf.org/PhotoEffort/AssociatedImages/Medium/Charles%20Edward%20Osborne.jpg http://assets.nydailynews.com/polopoly_fs/1.1463253!/img/httpImage/image.jpg_gen/derivatives/article_970/article-hiccup-0921.jpg http