A skeleton riddle was posted on the newsgroup alt.humor on September 29, 2000:

Q: Why didn’t the skeleton eat the cafeteria food?
A: Because he didn’t have the stomach for it!

A similar skeleton riddle (about Halloween candy) has been cited in print since at least 2012:

Q: Why didn’t the skeleton like the Halloween candy?
A: He didn’t have the stomach for it.


Google Groups: alt.humor
Looking for halloween material
fmhlaw
9/29/00
(...)
Why didn’t the skeleton eat the cafeteria food?
Because he didn’t have the stomach for it!

Google Groups: alt.humor.puns
“Puns of the Weak” 10/20/00
Stan Kegel
10/21/00
(...)
Why didn’t the skeleton attend the banquet? He didn’t have the stomach for it (By Gary Hallock)

Google Books
Spooky Sillies:
A Book of Ghost Jokes
By Mark Moore
Minneapolis, MN: Picture Window Books
2005
Pg. 7:
Why didn’t the skeleton eat the cafeteria food?
Because he didn’t have the stomach for it.

Google Books
December 2012, Boys’ Life, “Think & Grin,” pg. 63, col. 3:
John: Why didn’t the skeleton like the Halloween candy?
Mark: Why?
John: He didn’t have the stomach for it!
John Capelli, Houston, Texas

Twitter
insanescouter
@insanescouter
#ScoutHumor John: Why didn’t the skeleton like the Halloween candy? Mark: Why? John: He didn’t have the stomach for it!
5:10 PM · Feb 23, 2016·Hootsuite

Twitter
ScoutBot
@ScoutBot
#ScoutHumor John: Why didn’t the skeleton like the Halloween candy? Mark: Why? John: He didn’t have the stomach for it!
5:15 PM · Feb 23, 2016·Hootsuite

Twitter
JDL-evision
@JasonDLouie
@kararoyster Did you hear about the skeleton who turned down all of the candy he was offered?
Turns out he didn’t have the stomach for it.
6:06 PM · Oct 10, 2017·Twitter Web App

Twitter
tess cook‏
@Tessbc7
why couldn’t the skeleton eat any halloween candy??
He didn’t have the stomach for it
11:03 AM - 14 Oct 2017

Twitter
BRITÁNICO
@elbritanico
#Joke
Q: Why didn’t the skeleton like the Halloween candy?
A: He didn’t have the stomach for it!
12:48 PM · Oct 17, 2017·Twitter Web Client

Twitter
M👻urning Sunrise
@Dawni_Darko
Replying to @Alex_Polinsky
Why don’t skeletons like Halloween candy?
They don’t have the stomach for it!!! Get it??!! 🤣💀👻
1:18 AM · Oct 3, 2019·Twitter Web App

Reddit—Dadjokes
Posted by u/Vickiluna69 September 13, 2022
Why don’t skeletons like Halloween candy? 🎃🍭
They don’t have the stomach for it 😂🤪

Twitter
Jimmy RevJim Olsen
@mybuddyjimmy
Why don’t skeletons like Halloween candy? They don’t have the stomach for it! #LaughoftheDay
9:26 PM · Oct 23, 2022 from Des Moines, IA·Twitter for iPhone

Twitter
GNolan
@GNolan01
Why don’t skeletons like Halloween candy?
They don’t have the stomach for it!
1:36 AM · Oct 24, 2022·Twitter Web App