“In the weeds”

“In the weeds” is restaurant slang for “lost,’ meaning that a waiter or waitress is so swamped with work that he or she is “lost in the weeds” and can’t possibly do all the work. The origin of the slang is unknown, but it seems to have existed since at least the 1970s.
 
 
Wikipedia: Diner lingo
Diner Lingo is a kind of verbal shorthand used by cooks and chefs in diners and diner-style restaurants, as well as Waffle Houses
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In the weeds: a waitress/cook that can’t keep up with the tables.
 
Glossary of Restaurant Industry Terms
In the Weeds
A colloquial expression used when persons are near or beyond their capacity to handle a situation or cannot catch up. Struggling. Very busy.
   
Google Books
The Dictionary of American Food and Drink
By John F. Mariani
Published by Ticknor & Fields
1983
Pg. 210:
in the weeds. Restaurant waiter’s lingo for having too much work to do that night.
     
14 April 1985, Los Angeles (CA) Times, “For those who tip and those who are tipped, it’s simply a matter of good business” by Jack Smith, View section 6, pg. 1:
“I had a T-shirt at Friday’s that said, “W/W’s do it in the weeds.”
(T.G.I. Friday’s restaurant. W/W is waiter/waitress—ed.)
 
24 June 1998, New York (NY) Times, “The First Job: Out of the Frying Pan, Into the Fire” by Eric Asimov, pg. F8:
Anger may be the only recourse when you’re “in the weeds,” as chefs call the nightmare of not being ready when orders pour in and you fall behind and can’t see a way out. Ferocity may lie behind the reports that one famous French chef prods his workers with a fork to get them to go faster. Intensity and purposefulness drive chefs to be demanding, not compassionate.
 
Google Books
Sundae Best: a history of soda fountains
By Anne Cooper Funderburg
Published by Popular Press
2001
Pg. 169 (Hash-House Grrek):
IN THE WEEDS: The fountain or counter is swamped with customers.
   
Google Books
The Encyclopedia of Restaurant Forms:
A complete kit of ready-to-use checklists, worksheets, and training aids for a successful food service operation

By Douglas Robert Brown
Published by Atlantic Publishing Company
2004
Pg. 2 (Chapter Six—Food Service Terminology):
IN THE WEEDS: Extremely busy (one step below being buried).
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WEED-EATER: A helpful person who assists others “out of the weeds.”
     
Chow.com
Decoding Diner Lingo
I’ll have a shingle with a shimmy and a shake in the alley

By Kate Ramos
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In the Weeds = when a worker is overloaded. Jane Sherman has been a waitress at the Tastee Diner in Laurel, Maryland, since 1978, and this is the only term she ever remembers using. “We say that all the time when we can’t keep up with our tables,” she explains. The term refers to the military roots of many diner chefs: When a regiment was in the weeds, it meant the soldiers were in danger of being slaughtered.
Published June 18, 2007
   
New York (NY) Times
November 18, 2007
The Food of Love
By SEAN WILSEY
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“It was Chef Keller. Apparently, he had stepped in to relieve the dishwasher, who had also found himself in the weeds.” (“In the weeds” is kitchen slang for falling behind.)