You're allergic to meat.
(I want to mention that I know lactose intolerant people can eat meat, unless it's milksteak.)
You're a Triceratops, and then you're cool enough not to ned meat.
You don't consider eating animals as eating meat.
(Did you notice how cute my pictures are?)
Honorable mention to: You're in a coma, your mom is a NY strip steak, and you had a great reason but it's been so long you don't remember.