“Why don’t they serve chocolate in prison?”/“Because it makes you break out.”

Chocolate has a reputation (perhaps undeserved) for giving some people acne. There’s a “chocolate makes you break out” pun:
 
Q: Why don’t they serve chocolate in prison?
A: Because it makes you break out!
 
The joke has been cited in print since at least 2000.
 
     
Wikipedia: Acne vulgaris
Diet
The relationship between diet and acne is unclear, as there is no high-quality evidence which establishes any definitive link. High-glycemic-load diets have been found to have different degrees of effect on acne severity by different studies. Multiple randomized controlled trials and nonrandomized studies have found a lower-glycemic-load diet to be effective in reducing acne. Additionally, there is weak observational evidence suggesting that dairy milk consumption is positively associated with a higher incidence and severity of acne. Effects from other potentially contributing dietary factors, such as consumption of chocolate or salt, are not supported by the evidence. Chocolate does contain varying amounts of sugar, which can lead to a high glycemic load, and it can be made with or without milk. There may be a relationship between acne and insulin metabolism, and one trial found a relationship between acne and obesity. Vitamin B12 may trigger skin outbreaks similar to acne (acneiform eruptions), or exacerbate existing acne, when taken in doses exceeding the recommended daily intake.
 
Google Groups: alt.humor.puns
“Puns of the Weak” 6-30-00
Stan Kegel
7/1/00
(...)
Why don’t they serve chocolate in prison? Because it makes you break out. (Paul Benoit)
     
19 November 2004, New Castle (PA) News, “The Puzzle Place,” pg. B7, col. 2:
Q. Why don’t they serve chocolate in prison?
A. Because it makes you break out!
 
Google Books
Just Jokes:
A Collection of Kids Jokes
By Phyllis Agles-Johnson
Raleigh, NC: LULU Publishing
2010
Pg. 26:
Q. Why don’t they serve chocolate in prison?
A. Because it makes you break out!
 
Twitter
thavil ngamthet
‏@khawfarng
Q. Why don’t they serve chocolate in prison?
A. Because it makes you break out!
8:53 AM - 22 Feb 2010
 
Twitter
Vitzel Trevino
‏@Uhhhhlexis
Why don’t they serve chocolate in prison? Because it makes you break out. LOLgasm!
1:49 PM - 2 Apr 2010
   
Goddytech
250 Stupid Jokes That Are Very Funny
KAMERZOOM
DECEMBER 16, 2015
(...)
31. Q. Why don’t they serve chocolate in prison?
A. Because it makes you break out!