Jester's magic was a tradition of arcane magic commonly practiced by jesters and clowns in and around Waterdeep. It focused on magical pranks and jests that could send a target to sleep or rouse them to laughter, or even put them in stitches.
To learn jester's magic, one had to be highly trained in acting and foolery and know how to cast arcane spells. They could be either bards, making up the bardic jester tradition, or they could be sorcerers or wizards, making up the jester mage tradition.
Masters of jester's magic were more potent in certain spells of their chosen tradition. For the bardic jester tradition, these were prestidigitation, remove fear, hypnotism, Tasha's hideous laughter, calm emotions, enthrall, confusion, glibness, modify memory, mass suggestion, and Otto's irresistible dance. For the jester mage tradition, these were prestidigitation, grease, hypnotism, Tasha's hideous laughter, rope trick, deep slumber, suggestion, confusion, seeming, mass suggestion, project image, Otto's irresistible dance, and weird.