James Comey Down on the Dance Floor at D.C. Wedding!!!

James Comey may no longer head up the FBI, but he was the director of boogie at a wedding Saturday night.

Donald Trump's nemesis hit up a D.C. wedding and showed off some moves to the 300 guests.

Comey followed proper etiquette ... removing his jacket and loosening his tie before hitting the dance floor.

We don't know the relationship between Comey and the bridal families ... but he stayed a while and guests tell us he had great time.