To Jessica Simpson, it's all about the butt.

The songbird/budding clothing mogul had a comment about just about every "model" that worked her catwalk Tuesday evening.

"You were obsessed with those forever skinny jeans," Simpson said to "model" KaCee Cobb. "Show us your butt!" (Cobb obliged.)

"Everybody wants a pair of jeans that makes their butt look good," Simpson told StyleList. "And if they don't want their butt to look good they want their thighs to look skinny." She shared the fitting tip that ensures that – "You always have to make sure you take in the knee. Trust me, I have been through so many fits and designs."

Simpson's event, held in her midtown showroom, celebrated the recent launch of her jeanswear collection and gave party-goers a peek at her spring collection which is more of the same. There are cute denim dresses and knit tops, but the piece de resistance was a fitted camouflage jacket.

Even better, it gave a rare glimpse into who she considers her inner circle. Her models were the women nearest and dearest to her – her publicist, the girl she babysat when she was younger, her personal assistant, her hair person, her make-up person and her sister, Ashley Simpson Wentz.

For more Spring 2011 Fashion Week news, click here.