Magic Mirrors

There were 3 girls, a redhead, a brunette, and a blonde. There was this magic mirror, and if you said a lie in front of it, you would disappear.
The redhead went up to it and said "I am the prettiest girl in the world" Poof, she disappeared.
The brunette went up to the mirror and said "I think I am the prettiest girl in the world" Poof, she disappeared.
The blonde went up to the mirror and said "I Think..." Poof she disappeared.