When was the last time you laughed? Chances are, you've already done it today. Laughter has social, psychological and physiological functions -- some researchers are even looking to use laughs in therapy. Our need to laugh has received more attention in recent years, and we've got hundreds of comedy sitcoms and movies to prove it. Whether you giggle, chuckle, howl or snort, your funny bone is a fascinating repertoire to study. Test who will have the last laugh: you or the Ultimate Laughter Quiz.