Michael Phelps was having a grand old time in Las Vegas this past Monday and decided to let his hair down a bit when he visited XS nightclub. The 6-foot-4-inch, 185-pound Olympic medalist swimmer was on stage and tried with friend to hop in an inflatable raft with the idea being to crowd-surf. However, things didn’t go as planned and Phelps fell backwards to the ground a couple seconds into the attempt.