She's An Uptown Girl

I got this invitation emailed to me today. I totally want to go... mostly because there will be cocktails and good people watching. But then I read the dress code: Uptown Chic.

What is that exactly? Does DC do Uptown... do I need to take out the vintage Chanel suit and and have Jeeves the driver take me while sipping a gin martini? I'm so funny sometimes even I laugh out loud.