Even though these Burchell"s zebras are probably fighting, to us it kind of looks like they are sharing a laugh. And since today is World Laughter Day, we"ve been trying to imagine what kind of joke would make a zebra laugh. Why did the lion spit out the clown? Because he tasted funny. Maybe. Anyway, World Laughter Day is celebrated on the first Sunday of May to remind people of the very real physical and mental health benefits of laughter. It"s no joke that laughter has a clinically proven positive effect on your well-being. And experts (yes, there are experts) agree that laughing lowers blood pressure, releases endorphins, works your abs, reduces stress hormones, and even boosts T cells that fight infection. Faking it still works, even if you"re not feeling it.