Pranksters are people who come up with and perform various jokes to surprise or amuse others. Sometimes their antics, or pranks, can be simply funny: for example, someone might substitute lemonade with a bitter taste instead of a drink for a friend. This is what pranks are — different tricks that can elicit a smile or even laughter.
But pranksters can also engage in so-called social experiments. These are more serious antics that usually aim to test people's reactions to certain situations or to highlight some social issues. For example, a prankster might stage a scene where he pretends to be homeless and observes how people react to his request for help. Thus, a prankster is not only a joker but also, perhaps, a researcher of human behavior.
So, pranksters are like artist-jokers who, through their antics, aim to evoke emotions in people. Depending on the form, their pranks can be both light-hearted jokes and deep social experiments that provoke thought.