Growing up: everybody does it sooner or later, and it comes with its benefits and its drawbacks. For example, no one can make you go to bed, but you're going to feel your decision in the morning. No one can make you clean your room, but you have to pay to keep the lights on. You don't have homework, but you have a job. Never fear! Adulthood doesn't have to be all drudgery and paperwork. Take a cue from these folks who know how to tap back into their kid sides and have some fun. 1.) Learn (or teach someone)...