Fitness guru Tracy Anderson enjoyed a 39th surprise birthday in a private lounge at The Chester Monday, despite a minor fashion mishap.
“Tracy was wearing a black Alexander Wang dress, which she didn’t realize was see-through until all the photo flashes went off when she walked in,” said a spy. “Everyone noticed because she wasn’t wearing a bra. She laughed about it when they told her.”
Some 60 guests “were having dance-offs . . . It looked like one of her cardio classes.”