Intoxicated or exhilarated to an important degree (1939+)
The Dictionary of American Slang, Fourth Edition by Barbara Ann Kipfer, PhD. and Robert L. Chapman, Ph.D. Copyright (C) 2007 by HarperCollins Publishers. Cite This Source
Idioms and Phrases with high as a kite
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.