That fairy tale ending with a knight in shining armor
She can be my Sleeping Beauty
I'm gon' put her in a coma (Woo!)
Sleeping Beauty was just that; a sleeping beautiful woman (as a coma is a constant slumber).
This was probably meant to mean that sex with him would be so great that the she would turn into sleeping beauty because she would be so worn out.
However, unfortunately, the metaphor comes across a bit odd, as in Sleeping Beauty an evil witch (Maleficent — seen below) puts her in a coma; and the knight in shining armor gets her out of it by kissing her. And that is the fairytale ending.
Sleeping Beauty, being awoken from her slumber by her knight in shining armor, as opposed to being put into one (also note this picture casts Vanessa Hudgens and Zac Efron into those roles for some reason).
To help improve the meaning of these lyrics, visit "Dark Horse" by Katy Perry (Ft. Juicy J) Lyrics and leave a comment on the lyrics box