Conan O'Brien delivers his monologue during the special Halloween night slelevision episode of Late Night.

Move over, Nicole Richie, Posh Spice and that skinny Olsen twin -- Conan O'Brien is going "skelevision."

Tonight's special Halloween episode of Late Night With Conan O'Brien (12:35 a.m. on A-Channel and NBC Buffalo affiliate WGRZ) will be performed entirely with skeletons.

It is one of those crazy ideas that usually cracks people up in a writer's room and then never sees the light of day -- except on O'Brien's up-for-anything little show.

Over the past 13 seasons, O'Brien and company have never shied away from turning Late Night inside out. They seem to do this as much to keep themselves keen as to shake up their audience. As O'Brien told me a couple of years ago when he took his show to Toronto, "From the beginning we always tried to make this show where it's not safe to turn it off."

There have been some pretty out-there examples over the years. One Late Night episode was done entirely in claymation, like an old, extended Mr. Bill cartoon from Saturday Night Live. Another was retooled as an infomercial, with O'Brien in a really loud sweater pitching the 10th anniversary DVD of the series.

Then there was the time they broadcast an entire show from one of those Circle Line ferries that rings Manhattan. During New York's 2003 blackout, they did a last-minute, 15-minute version of the show using nothing but reserve power.

Other late-night talk shows have thought outside the box in the past. Diehard Letterman fans will recall the time he broadcast an entire hour in Spanish, or the time the entire screen slowly rotated 360 degrees over the course of the hour (people who tuned in halfway through saw an upside-down Peter Ustinov). TV repair shops were flooded with calls.

After 50 years, so much of late night is the same old same old -- the desk, the band, the monologue -- that shows such as Letterman and O'Brien have to shake things up just to keep everybody honest. Torontonians will recall the week-long O'Brien orgy that hit this city early in 2004. O'Brien recently rocked Chicago with a similar road trip. Then there was that wacky, hour-long travelogue to Finland to meet look-a-like Finnish president Tarja Halonen,

REAL EPISODE

But skeletons? "This may be the finest hour of television NBC has ever produced ... with skeletons," O'Brien said in a press statement. He didn't say, "It takes guts to do a show with skeletons," so I'll say it for him.

The idea is to take an episode from last May, which featured guests Larry King, Omar Epps (House) and actress and pole-dancing workout instructor Sheila Kelley, and re-do the visuals with skeleton puppets. Toronto-born Will Arnett (Arrested Development) will also be "skeletized" with O'Brien in the opening "In The Year 2000" bit.

While no preview screener was made available to press, the stills from the show (surrounding this story) look pretty damn funny. Check out King's red suspenders on his skeleton. If anything, the CNN host looks healthier than usual.

O'Brien's skeleton, of course, is sporting a big red wig. The purple tie is a classy touch.

Will this get old in about two minutes? Taking stupid to its ridiculous conclusion has always been part of O'Brien's charm.

After 2,000-plus hours, O'Brien has to do something while he waits to take over Jay Leno's hosting duties on The Tonight Show (scheduled to occur in 2009).

"Most nights, you're looking for anything," O'Brien confided to the Sun in 2004. "Someone told me that Johnny Carson once broke into a card trick spontaneously on the air. In the commercial break, the guest said, 'Wow, that was really cool.' And Johnny said, 'When you have a job like this, you eventually use everything you've got.'"

Everything, right down to the bare bones.