To dance or have fun.

I'm not sure if anyone ever used this expression seriously. It's usually used in a silly/ironic sense now to "party hard" or "dance hard."

It is slang specific to the Black American community. I think it can mean A. to dance in a specific style, or B. to have sex.

This is from the Will Smith song. At the time it came out, many people thought that it had a sexual meaning, but it really meant to display impressive style, for example, by the clothes you wear, the way you dance, the things you do socially.

I always heard it as 'gettin' jiggy with it' Here is the definition that I know the phrase by: http://onlineslangdictionary.com/meaning-definition-of/get-jiggy-with-it I don't believe that it's specifically black American slang. I heard whites say it back in the '90s. It's a dated phrase. I don't know the entire history of the phrase but I'm pretty sure that it pre-dates the song by Will Smith. I've read that originally it had a sexual meaning. With that said, Elizabeth did not deserve any downvotes. Get real people. If you downvote then please have the courtesy to give your explanation.