Pikachu's original name was Pikapi. But when all the Pikapi in the wold got infected by a cold they weren't able to cure it. As a result. Every time they sneeze, it sounds like "pika-chu". So they became Pikachu's. You don't have to fake a laugh at this you know. I know it's lame. But it's funny to me and my friends. Pika-Pika-CHUUUUUUUUUUUUUUUUUUUUU