She's some seriously buff stuff!

Looking like she could lift a car with one hand, Jessica Simpson showed off her bathing suit bod' when she shared a new Instagram pic on Monday.

Along with the pic of her in a sexy one piece, Jessica wrote, "Oh yea girl...We are proud to be in our bathing suits!! @baylormcg #hardworkpaysoff #workoutpartnersforlife."

The sexy snap was taken during sister Ashlee Simpson's bridal shower at Jess' Los Angeles home over the weekend.

Way to show up your baby sis, JS!