Justin Timberlake recently joined a group of 25 people for a night out at the Crystal Cologne club in Cologne, Germany where he performed a pair of concerts for The 20/20 Experience World Tour on Sunday and Tuesday! Ach du lieber! Although Justin was invited to get free drinks there, he left a tip over $4,000 for a group of waitresses working there. Justin apparently stayed until 4:30 a.m.. According to one of the waitresses it was pretty shocking. She said,”We were all really amazed.”