In Dragon #65 Gary Gygax wrote the following in the Jester:
JESTER -- Rob Kuntz, in his currently unpublished module, The Tower of Zaeen, has included a jester. A recent DRAGON Magazine (issue #60) also included the Jester as an NPC class. Because I have also considered the jester as an actual class for the game, I have not as yet read either description. Jesters, as I envision them, can be of human, gnome, or halfling race. (Elves could never permit themselves to be so debased; dwarves are far too serious and just plain humourless.) Alignment is as desired by the player. A jester would have a combination of verbal, magical, and acrobatic skills which allow the class to be viable even though there is no great power. Verbal skills would enable the character to influence many creatures toward kindliness, humor, forgetfulness, thoughtful consideration, irritation, anger, or even rage. Magical skills would have to do with jokes and tricks -- sort of a directed wand of wonder with some magic-user spells and illusionist magic tossed in. Acrobatic skills would be mainly tumbling and juggling, with some magic tossed in there as well. Level titles are: Wag, Punster, Masquer, Harlequin, Clown, Juggler, Buffoon, Fool, Joker, Jester. Powerful at its upper levels, the class will be less than popular with fellow adventurers, I suspect, so that jesters will frequently have enemies and travel alone....
I was a little surprised to see the Jester appear as a Prestige Class in the Players Guide to Blackmoor (3.5E), but it may have been a nod to the original Roger Moore article. Entertainers have always existed in Blackmoor of course, ever since the heroes allowed a circus to perform in the courtyard of Castle Blackmoor. More ideas on the Jesters of Blackmoor can be found here.