There is no one definitive answer to why people laugh when they get tickled. Some theories suggest that it is a response to a social stimulus, such as being touched in an unexpected or playful way. Others believe that it may be a result of the body's natural response to being stimulated, such as the release of endorphins which have mood-boosting effects. Additionally, laughter can be a form of communication, signaling that someone is enjoying the experience or wants to build social connections. Ultimately, the act of laughing when tickled is likely a combination of physical and social factors.