Pikachu is based on a legend in japan Raiju . It has a body of lightning crackling around it. Its usually drawn like a dog or wolf, but it can look like a non-cool animal. You know some people sleep on their left or right side and surrounded by pillows?( I do that). The raiju does that but in your flesh wonderful-...I mean horrible it likes to sleep in your belly button. So that means an outie is better than an innie. The problem is, when the thunder god Raijin wants to wake up his pet Raiju he would shoot lightning arrows at it. This can result in a rotten day for the person to whom the navel belongs to. So some people perfer to sleep on the stomach when there is a storm from a raiju crawling in there .