A shirtskirt! You can make one in 10 min with an old, oversized men´s shirt, a bit of thread and elastic band. Cut the shirt according to the desired length (stitch elastic at the top) and fold the top with elastic band. Sew the arms together to serve as a belt/sash and add a few belt loops from the excess fabric.
Turn a men's long sleeved shirt into a chic blouse. I'd add straps to cover bra straps and also avoid embarrassing pull-ups. Maybe add contrasting binding to finish the edges that also work to conceal the elastic.