IN its decade on the market, the Spanx line of modern girdles has become both a must-have undergarment and an easy punch line. Celebrities like Tyra Banks, Janeane Garofalo and Wanda Sykes declare their allegiance to Spanx, even as they joke about it.

“It sucks all that stuff in,” Ms. Sykes said recently. “It’s so funny that when you take them off you just become a blob. You look in the mirror, and it’s like, hey, now I’m an amoeba.”

The snickering rose a decibel level in February, when Spanx introduced its first products for men. On “Jimmy Kimmel Live,” the host was nearly ejected from his own Handsome Men’s Club after Rob Lowe accused him of wearing Spanx. Cue giggles from the audience and a horrified look from another club member, Matthew McConaughey, his tight abs unexposed for once. (Read More).