Laughter means the same thing in the U.S. as it does in India, Australia, Russia, and everywhere else on earth. In fact, it's not even a distinctly human trait—apes chuckle too.
But all laughter isn't created equal. Laughter (and other vocal expressions) used to be more closely tied to how we feel, but as we evolved, we learned to fake it in order to speed up the bonding process. However researchers recently showed we can tell whether giggles are genuine or phony. A new study even suggests we're able to judge whether people are friends or strangers based on how they laugh around each other.
(h/t The Conversation)