tight as a tick
Drunk, as in She was tight as a tick after just one glass of wine. This expression alludes to a tick engorged with the blood of the animals it feeds on. [Slang; mid-1800s]
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.