A jokester is someone who loves telling jokes, joking around, or playing practical jokes on people. You might tire of your jokester uncle pretending to "get your nose" every time you see him.
The teacher who's fond of knock-knock jokes is a jokester, and the student who puts a whoopie cushion on that teacher's chair is also a jokester. A career as a stand-up comedian might be in one of these jokesters' future. Jokester dates from about 1819, combining joke, from its Latin root iocus, "joke, sport, or pastime," and the suffix -ster, used to mean "a person who..."