Britney Spears Takes Off Pants, Steals From Porn Shop

So she's not pregnant. Britney Spears is still insane, however.

The latest puzzling antics from the alleged singer? Shortly before 1 a.m. on November 18, Spears entered the X-rated Hustler Store in W. Hollywood.

There, she loaded up on naughty skivvies and headed to the fitting rooms. But store employees "told [Britney Spears] they don't allow people to try on underwear," a source at the scene says. "She was really upset."

The source adds: "She looked out of it. There was nothing going on behind her eyes." Which distinguishes this from any other day ... not at all!

Then, the kinky sex fiend threw a fit, took off her pants and underwear as she tried on a pair of boyshorts (with "Barely Legal" stitched across the rear end) in the middle of the store while 15 other shocked customers looked on.

An eyewitness tells Us Weekly that the scene Britney caused was ridiculous: "The employees kept saying 'Don't change out here!' She's just like, 'Well, I couldn't take them in the fitting room' ... It was like dealing with a child."

Britney Spears' tantrum only worsened.

"The staff told her she had to pay, and she rolled her eyes, but paid with a credit card," the source says. "As payback, on her way out, she went up to a mannequin, snatched the wig off the head, and stole it!"

So, to sum up, Britney Spears took off her pants and underwear in an X-Rated sex shop, then got pissed when the staff told her she was out of line, then shoplifted from it. We await a Sam Lutfi text message commenting on the matter.