Let's go swing dancing!
One or two hundred people get together once or twice a week to dance it up. It's a great environment, friendly to new dancers, or "non-dancers". They've got classes before hand if you want to learn something or break some ice. Let's go.
Here's what it looks like: http://youtu.be/7IoEWQRdl0M?t=59s
And here's a quintessential clip: http://youtu.be/qkthxBsIeGQ
If you want to take a class, there is a cost. It's $15 for a class [and it includes the dance, afterward]. Their calendar has more classes and details. The beginning class starts at 7:45.
After the classes, lots more people show up to dance to the DJ-ed music. If you're sorta shy, well lots of people are, but you can stick with the Nerds until you warm up to the place!
The price is included with a class. It's $10 for just the dance ($8 for students w/ ID). Music starts up at 8:30 and goes until, maybe 2am. People from the classes often hang around, and other people show up. Everybody's really pretty friendly.
To get there, check out this map: http://atomicballroom.com/location-information.php Trust me, look at it. It'll save you time.