Julia Garner -- who has been tapped to play Madonna in her upcoming biopic -- shows she's got the Material Girl vibe ... showing up at a drag show, and even getting in on the action!
Drag Queen Ginger Douglas tells TMZ ... Julia was having a blast at Mickey's in WeHo during a performance of "Showgirls," put on by "RuPaul's Drag Race" star Morgan McMichaels.
Julia, her hubby Mark Foster from Foster The People and the rest of her pals sat front row ... Morgan even pulled her up on stage, congratulating her for her Madge flick ... and the crowd went wild.
Julia stayed for the whole show -- feeling the performances and even tipping the drag queens. She stayed after the show to take pics with members of the audience and some of the performers.
Madonna would approve!!!