Britney Spears was supposed to host the Billboard music awards in Vegas with Paris Hilton next week, and their people were in negotiations for it, but Britney pulled out with no explanation.

Speculation is rampant that Britney has soured on Paris, but the more likely explanation is that someone took her aside and told her to get her shit together, put on some panties, and stay at home with her kids for a couple of nights. Making a scheduled public appearance with Paris will only remind everyone of the three separate sets of punane-baring pictures of Britney that are floating around on the web. (If you don’t believe me that she did it three different times, just look at the clothes she’s wearing in each picture series linked above.)

After nearly a week of clubbing, partying and shopping in LA with new BFF, Paris Hilton, Us has learned exclusively that Britney Spears has abruptly pulled out of co-hosting with the heiress on the Fox Billboard Music Awards, scheduled to air live on December 4.

“She pulled out,” confirms a source with Fox. “She didn’t give a reason.”

The source tells Us that Hilton is still a possible host despite losing Spears as a sidekick. Other sources confirm that as recent as this morning, agents for both Hilton and Spears were hashing out the final terms of the contract, but at 5pm today, Spears had backed out of negotiations.

“We really don’t know the reason. But we’re disappointed she backed out.” says a Fox source.

Brad Garrett, the big guy from “Everybody Loves Raymond” is the potential replacement for Paris and Britney, so it’s not like it’s a prestigious hosting gig. Paris may also host solo.

Why are all these lesser music awards using inexperienced hosts like Lindsay and Paris? Maybe no one watches them, but a 20-something celebrity known for her skill in partying and shopping is not a good choice to host an awards show.

Britney was seen leaving a restaurant on Monday night with a fur coat on and a wine glass in her hand before she got in her car and had trouble finding the ignition. She wore a yellow knit cap to hide her shedding extensions and had glasses on in a vain attempt to look studious. She was photographed at some other point that night with an orange tank top on and no bra.

Meanwhile Paris, Britney and Lohan are no longer the three slutsketeers after Paris and Lohan are said to have fought it out at Hyde Monday night. Paris is said to have told Lohan “you’re a fucking coked-out whore; don’t ever say you’re my friend again!” with Lohan leaving all upset.

Oh boo hoo. Go buy some more sex toys and get photographed again Lohan. That coochie-showing trick is completely old. Or maybe you could visit a library or a book store. That might be a good way to get some attention.

Britney actually stayed home last night, Tuesday, as none of the paparazzi websites have pictures of her out. Or maybe they were all too freaking tired to keep up with her.

Here are photos of Paris, Britney and Lindsay on Monday. Lindsay is seen with a pair of $1,000 diamond-studded handcuffs since the help is so unreliable at keeping her men by her side. Pictures from Splash News Online.