Scrubs are thin pants and shirts, usually light blue in color, worn by doctors and nurses while operating on a patient. Also make good pajamas. Because of their excellent pajama nature, many hospitals have begun a checkout program for their scrubs, making sure not too many leave the premises. Apparently this was costing hospitals lots of money as several people casually brought home their scrubs, either by accident or on purpose.
(At least that's what my dad calls 'em, and he's a doc.)