In the snap, the body confident actress was rocking a pair of Minnie Mouse ears and a mauve T-shirt as she leaned over a balcony next to her pal. While her friend's plush monkey backpack was extremely cute, all eyes were on Winter's voluptuous booty, which was peeking out of her sassy Daisy Dukes.
If you got it, flaunt it, right?
ET caught up with Winter at Variety's Power Of Young Hollywood Issue Celebration in August, where she had no shame in explaining her risqué pic game.
"Everybody is so hyped up on the fact that I post photos where my butt's out. It's a butt. Everyone has a butt," she said. "I don't think it's crazy."
"It's like, 'Let me live!'" she added. "I'm enjoying my life, you're enjoying your life, you should be posting your butt if you like it, too!"
The 18-year-old actress currently covers the November issue of Seventeen magazine, and in her accompanying interview, she discusses the negative comments she receives on social media daily, while also revealing the real reason why she likes to show off her skin-baring curves on Instagram.