Disney darling Demi Lovato is being admitted into Seattle Grace Hospital as a schizophrenic for a guest spot on ABC's Grey's Anatomy.

Demi may be trying to shed her squeaky clean image by threatening her co-stars with a loaded hypodermic needle in this clip from the upcoming episode. Where's beau Joe Jonas when you need him?

A little known fact ... Demi's kid sister, Madison De La Garza, plays Eva Longoria's daughter on Desperate Housewives. Now that's a talented family!

Demi's Grey's Anatomy episode airs May 13.