down the hatch
Drink up, as in “Down the hatch,” said Bill, as they raised their glasses. This phrase, often used as a toast, employs hatch in the sense of “a trap door found on ships.” [Slang; c. 1930]
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.