Completely wrong, mistaken, as in If you think you can beat the system and win at roulette, you're all wet. The original allusion in this expression is unclear, that is, how moisture or dampness is related to wrongness. [Slang; first half of 1900s]
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
How to use all wet in a sentence
Hearn said, and took that all-wet, shivering creature into his own bosom (underneath the cloth) and kindly warmed it.The Life and Letters of Lafcadio Hearn, Volume 1 | Elizabeth Bisland