“Why did the chicken go to the gym?”/“To work on his pecks.”

Many people go to the gym to work on their “pecs” (pectoral muscles) and there’s a pun:
 
Q: Why did the chicken go to the gym?
A: To work on his pecks (pecs).
   
“Why did the chicken go to the gym?”—with no answer—was cited on Twitter on January 29, 2009. “Why did the chicken go to the gym? To work on his pecks” was cited on Twitter on September 3, 2011.
   
 
Twitter
parsnipnose3000
‏@parsnipnose3000
Ok. Another bad joke. I made this one up, so it’s extra bad. For the o35s out there. Why did the chicken go to the gym?
4:30 PM - 29 Jan 2009
 
Twitter
Billal Ali
‏@iambillal
Why did the chicken go to the gym? To work on his pecks.
5:58 PM - 3 Sep 2011
 
Twitter
Erik
‏@SeattleSeahack
Why did the chicken go to the gym? To work on his pecks. #ThankYouPS107AndGoodnight
3:10 PM - 18 Mar 2012
 
Facebook
Dad Jokes
August 9, 2012 ·
Why did the chicken go to the gym?.....to work on his pecks…..
(thanks Darryl)
 
Facebook
Dad Jokes
August 14, 2013 · Adelaide, SA, Australia ·
Why did the chicken join the gym?
To work on his pecks!
(thanks Stuart)
 
The Amazingly Lame Joke of the Day
Sunday, December 20, 2015
Why did the chicken go to the gym?
To work on his pecks!
Posted by Tim Wycislak at 10:52 AM