PAY ATTENTION to what is going on behind you.
People tend to relax and "play" when they think the photographer is not focusing on them. "Always turn around" constantly and be ready to snap a few quick photos. Don not get "tunnel vision" on the primary photo target. Notice the fun they are having and how it adds to this contemporary scene. I was actually taking photos of the bride in the other direction and simply turned around for a quick photo. I do this non-stop.
This photo just says PARTY to me and this group was a ton of fun!!! No posing required.