Drilling a hole in or removing a portion of the skullcase. When done medically, usually is intended to relieve pressure on the brain, but some have taken to doing it themselves at home (be sure to wear goggles to keep the blood out of your eyes!) claiming that having something like the soft spot in babies heads will help them regain some of the wonder and lucidity of childhood. Also the earliest known surgical procedure known to man, as evidenced from caveman fossils.