"Pumpkin” is sometimes punned as “pump kin.” A form of the “pump kin” joke was posted on the newsgroup rec.humor on May 21, 1990.

A Thanksgiving “redneck” riddle was posted on the newsgroup rec.humor on October 19, 1994:

Q: What do rednecks do for Thanksgiving?
A: Pump Kin.

A Halloween “redneck” riddle was posted on the newsgroup rec.humor on October 19, 1994:

Q: What do rednecks do at Hallowe’en?
A: PUMP KIN.


Google Groups: rec.humor
Humour
Al Donaldson
5/21/90
In article <35433@sequent.UUCP>, (Ed Wright) writes:
> Appalacia, Where many people have receeding chins and the same last name.

And on Halloween, pump kin.

Google Groups: rec.humor
Halloween joke
mus...@refine.enet.dec.com
9/20/90
What do West Virginia folk do to celebrate Halloween?
pump kin

Google Groups: rec.humor
Halloween Joke
Arthur Zards
10/15/91
What do hillbillies do on Halloween?
Pump-kin

Google Groups: rec.humor
WEST VIRGINIA JOKE
r562...@edinboro.edu
11/8/92
WHAT DO WEST VIRGINIANS LIKE TO DO OVER HALLOWEEN?
A. PUMP-KIN

Google Groups: rec.humor
WANTED Hick Jokes
Alex Filachionne
10/19/94
(...)
What do rednecks do for Thanksgiving?
Pump Kin

Google Groups: rec.humor
A now-out-of-season redneck joke (probably old)
Takao Ishinabe
11/3/94
What do rednecks do at Hallowe’en?
PUMP KIN

Google Groups: alt.tasteless.jokes
What do Rednecks do for Halloween??????
Pete
11/19/99
Answer: Pump Kin

Google Groups: alt.humor.puns
[Fwd: Submit: Halloween Riddles]
Stan Kegel
10/30/00
(...)
What do rednecks do on Halloween?
PUMP-kin (From The Placebo Page)

Google Books
Jeff Foxworthy’s Complete Redneck Dictionary:
All the Words You Thought You Knew the Meaning Of
By Jeff Foxworthy, et al.
New York, NY: Villard Books
2008
Pg. 265:
pump-kin (pamp’-kin), n. and v. a declaration about the capabilities of a device used for suctional or compressive transfer of liquid or air. “No way that little pumpkin fill up these tires.”

Twitter
jasperdett‏
@jasperdett
Redneck Halloween
spacer
Q: What do rednecks do on Halloween?
A: Pump kin.
7:18 PM - 10 Jun 2008

Google Books
Alexander The Great.
A Gayish Biography
By Dr. William Arnett
Woodpecker Media
2015
Pg. ?:
It wasn’t unusual for royalty to do what rednecks do on Halloween: pump kin.

Twitter
Jake Thornton‏
@jakethornton
Standard yearly Halloween Joke:
What do rednecks do on Halloween?
Pump kin.
You’re welcome.
1:03 PM - 31 Oct 2017