Actress Megan Fox has washboard abs, and guess what she does to show them off? She borrows clothes from her eight-year-old stepson Kassius.

The 24-year-old actress has been photographed in a tiny Star Wars top as well as a green Voltron number, which have also been worn in public by Kassius, reports dailymail.co.uk.

While the T-shirts look loose and baggy on Kassius, they are short and tight on Fox, who has always preferred a casual look with jeans and tops in her daily life, rather than girly dresses.

Fox became stepmother to Kassius - her husband Brian Austin Green's son from his relationship with actress Vanessa Marcil - when she married the former Beverley Hills, 90210, star in July.