A figure of speech involving the comparison of one thing with another thing of a different kind, used to make a description more emphatic or vivid (e.g., as brave as a lion , crazy like a fox ).
As fast as a cheetah. RAWR
As slow as a snail. OMG you are so slow
As dumb as a rock.
As blind as a bat.
Your as hot as Justin Bieber. HAHAHA just kidding, no one could ever be as hot and amazing as Justin Bieber, I mean look at this, yeah down there , that's right, I know your staring, who wouldn't.