“Shut up and squat” is a bodybuilding saying that has been printed on many images. “At least she was wearing a shirt that said Shut Up and Squat, nice shirt” was posted on the newsgroup misc.fitness.weights on August 15, 1996.
   
Similar “Shut up” expressions include “Shut up and train” and “Shut up and sing/dance/act.”
         
 
Google Groups: misc.fitness.weights
Thoughts from the gym
Rifle River
8/15/96
(...)       
At least she was wearing a shirt that said Shut Up and Squat, nice shirt. 
 
Google Groups: misc.fitness.weights
Cybergenics: replacements
Stefan Roehrig
3/14/97
(...)
Stefan ‘Shut Up and SQUAT!’ Roehrig - .(JavaScript must be enabled to view this email address)
 
Google Groups: misc.fitness.weights
Old T shirt slogans
Robert Schuh
7/28/00
(...)
Shut up and squat
 
28 July 2005, Atlanta (GA) Journal-Constitution, Buyer’s Edge sec., pg. SS17, col. 1 ad:
Shut Up and Squat
(Personal Training Studio)
912 Commercial Street . Conyers, GA 30012
 
29 April 2007,

(Annapolis, MD), “Tough workout with big benefits,” pg. F3”
“It does a little bit of everything - it’s great cardio, it builds muscle endurance and strengthens your muscle,” said Penny Arthur, owner of the Shut Up and Squat studio where Mr. Martin works out.
   
Twitter
James Stanier
@jstanier
Replying to @wossy
@Wossy shut up and squat!
1:57 PM - 4 Feb 2009
   
Twitter
Trey Zepeda
@treyzepeda
Throwing some kilo’s overhead with the snatch and then its time to Shut Up and Squat with my throwers-Uugh!
4:35 PM - 31 Mar 2009
   
Twitter
Vivek Bhaskar
@socraticinquiry
My golden mantra in the gym nowadays: SHUT UP & SQUAT. I’m hoping it’ll get me the results i want in 3 months time.Cheers!
4:03 AM - 19 May 2009
 
Twitter
\m/ 0.o \m/
@SKYSIXSIXSIX
SHUT UP AND SQUAT!! http://tinyurl.com/kwdnw5
12:08 AM - 9 Aug 2009
 
Twitter
L. Jeff Williams
@ljeffwilliams
Wanna #getFAT? Shut Up and SQUAT! Best exercise PERIOD!
http://bit.ly/cBD8FL
#Healthy #fit #Diet #exercise #personaltrainer #workout
9:01 AM - 5 Aug 2010
 
Twitter
Valentine Rawat
@RAWFIT
Strength Training Workout - Shut up and Squat http://fb.me/HdsUiK5u
7:27 AM - 14 Aug 2010
     
YouTube
Alon Gabbay - Shut Up and SQUAT (Leg day radikal)
Alon Gabbay
Published on Jul 11, 2014
   
NJ.com
King of boardwalk t-shirts: Wildwood shop owner has 6,480 for sale
Updated Jul 30, 2014; Posted Jul 21, 2014
By Peter Genovese .(JavaScript must be enabled to view this email address) ,
NJ Advance Media for NJ.com
(...)
So is pooping; popular shirts include “Potty Like a Rock Star,’’ “Shut Up and Squat’’ and the to-the-point “I Pooped.’‘
 
Google Books
The Secret Of Mind And Body:
The True Path To Obtain The Success With Simplicity Following The Right Strategies
By Oreste Maria Petrillo and Gianluca Pistore
Tektime
2017
Pg. ?:
“Carlos, listen, the only thing that you destroyed is your good sense. The leg extension and, then, how can you do an exercise called sissy squat? It’s an exercise for sissies. I’ve just four words for you ‘shut up and squat!’”
 
Twitter
GymAndGame
@Gym_Game_2018
SHUT UP AND SQUAT!!! 🏋️‍♂️💪😎
#sqaut #hacksquat #squatworkout
#legs #legday #legworkout
#gym #fitness #gymfitness
#gymlife #fitnesslife
#gymlifestyle #fitnesslifestyle
#gymboy #fitnessboy
#training #trainingday
#trainingworkout
#routine #dailyroutine
#flex #flexgym
1:13 PM - 6 Jul 2018 from Azul, Argentina