Madonna walked the Grammys red carpet in some sort of matador costume, and—whoops!—while adjusting the back of her skirt, she accidentally exposed her butt cheeks and thong underwear. She also revealed that she was wearing "an interesting piece of fabric beneath her muscular derriere to give her body part some added oomph," Us reports. She wasn't the only one whose underwear situation made headlines: Celebuzz is somehow aware that Chrissy Teigen went commando on the red carpet. Check them both out in the gallery, or click for the night's winners. (More Grammy Awards stories.)