Badtz-Maru

This mischievous little guy doesn’t like anything but himself, and he doesn’t mind saying so. So good at being bad! (But a nice guy deep down?) In Japanese "badtz" (batsu) is a term for "X", the cross signifying a wrong answer. "Maru" means circle or "O", and signifies a correct answer. Thus, his name literally means "wrong-correct," and is frequently represented by "XO". Badtz-Maru has many different facial expressions and poses, but he is classically recognized for pulling one eye down and sticking out his tongue, a gesture akin to sticking out one's tongue. His birthday is April 1st. He was created in 1993.

(Source: Sanrio.co.jp, Wikipedia)