1
general::
Phrase(s): *high as a kite [and] *high as the sky
1. Lit. very high. (*Also: as ~.) • The tree grew as high as a kite. • Our pet bird got outside and flew up high as the sky. 2. Fig. drunk or drugged. (*Also: as ~.) • Bill drank beer until he got as high as a kite. • The thieves were high as the sky on drugs.
McGrawhill's American Idioms And Phrasal Verbs
2
general::
Intoxicated, as by alcohol, as in After three beers she's high as a kite. The adjective high has been used in the sense of "drunk" since the early 1600s; the addition of kite dates from the early 1900s. The phrase is now used of disorientation due to any drug.
American Heritage Idioms