Sexy Jester

Ah, clowns, who likes those creeps? They're either scary as hell, or so silly you can't take them seriously. But what's this? A new character, donning motley that's just a little too tight, and Stripperiffic? Could this makeup-wearing joker actually be attractive? You can be damn sure that this character will be chock full of Fetish Fuel. Might be a Cute Mute if she's a mime. Usually a Manic Pixie Dream Girl for the heroes, or a Perky Female Minion for the bad guys.

Examples of Sexy Jester include:

Anime and Manga

As usual (like every Fan Service trope), Mahou Sensei Negima's cast contains one of these: Zazie Rainyday (pictured above) is a clown/mime girl with an talent for acrobatics, animal training and juggling. Her outfit for doing these things was clearly meant to invoke this image].
Busou Renkin has Papillon, maybe he's Fan Disservice to some, but a ripped, Stripperiffic villain who wears a male ballerina's outfit with a butterfly mask on seems to fit the jester motif.
Hunter X Hunter has the Bishonen Monster Clown Hisoka.
This is one of Sakura's costumes. Of course, when your costume designer is madly in love with you, what do you expect?
- Also, several of the Clow Cards themselves qualify as this.
Pierrot from Yakitate!! Japan counts too
Lazar's monster, Jester Queen in Yu-Gi-Oh! 5D's; she has a pretty decent rack there.

Comic Books

Harlene Quinzel, AKA Harley Quinn, lady love of The Joker
Jewelee, one of of the Punch and Jewelee villain duo, in The DCU.
The DCU has had multiple villains called Harlequin (mostly foes of Green Lantern) who all fit this description.
The Joker's Daughter, one-time member of the Teen Titans.

Tabletop Games

The Eldar Harlequins are super flexible, psychic, quite lax about clothing, and can melt you from the inside out with a giant needle.

Video Games

Kefka is quite a Bishonen in concept art.
- The game too. Remove the white/purple skin (or keep it if that's your thing) and he could be quite the looker.
Harle of Chrono Cross wears a mostly skintight outfit, and "pants" that cover her legs, but are completely transparent.
In City of Heroes, The Carnival of Shadows is mostly staffed with these.
Dragon Quest III has Jesters as a character class. Male Jesters are clowns in pink and purple pinstripes, while female Jesters wear Playboy Bunny outfits. To top it off, the Personality system used in the various remakes makes it possible to have a literal Sexy Jester.
A good portion of the NiGHTS fanbase thinks this about Reala, and Ni GHTS itself to some extent.
Adventure Quest Worlds has holiday/Christmas jester outfits which look like cut-open leotards on female characters. The very first version had the stomach and most of the breasts exposed.

Web Comics

Maytag, the fanservice queen of Flipside.

Western Animation

Harley Quinn. Batman may not notice, but The Joker sure does. The Joker himself occasionally counts, especially when Heath Ledger (and to a lesser extant Mark Hamill) played him.
- In her own series, Harley is a lot more risque.
Clopin from Disney's The Hunchback of Notre Dame, though he probably wasn't intended to attract as many fangirls as he did.

Real Life

This combines the Sexy Jester with Body Paint.
Typically averted with Commedia Dell'Arte. In contrast to all the sexy female "Harlequins" alluded to above, the original Harlequin (or Arlecchino) was a man, and one usually portrayed as romantically hapless.