This is categorized as a "clever tatoo" but I would also categorize it as humorous tattoo art. Tattoos like this show the committment of the individual to keeping humor at the forefront in their life. This tattoo is hilarious to me.
Every letter and numeral in English is in this diagram. Every English language book you've ever read is right there. *brain explodes* edited to add: if you can't find a letter, read the comments, someone has probably explained where to find what you're l