It's not sexist. It's a joke. They aren't saying it's a fact, they're just joking about it. I'm a white female and haven't had Starbucks since I was five ( a delicious hot chocolate BTW ) and I still find this and stuff like it hilarious. Because stereotypes are funny as long as they aren't treated as fact.
Problem is.. there's a 80% chance you get a shallow girl.. with a selfie-filled instagram, leggings, and a sweater... dont forget the infinity scarf. (Although.. i do love starbucks xD)
P.S (im black)