Thigh slappers refer to something that is hilariously funny. If you want to expand your vocabulary and use different expressions to describe something funny, you can use synonyms like belly-laugh, rib-tickling, side-splitting, knee-slapping, gut-busting, roisterous, uproarious, or sidesplitting. These terms are often used to describe jokes, stories, or situations that evoke strong laughter and merriment. Instead of using the same old term over and over, try these different phrases to add variety to your description and keep your audience entertained. So the next time you find something excessively humorous, use these synonyms to describe it and make your listeners laugh along with you.