Above, a 1934 plaque from the Big Apple Night Club at West 135th Street and Seventh Avenue in Harlem. Discarded as trash in 2006. Now a Popeye's fast food restaurant on Google Maps.

Entry from December 03, 2015
“What do you get when you divide the circumference of a pumpkin by its diameter?”

A popular joke told over Halloween and Thanksgiving is:

Q: What do you get when you divide the circumference of a pumpkin by its diameter?
A: Pumpkin pi.

The joke has been cited in print since at least 1998.

“What do you get when you take green cheese and divide its circumference by its diameter?"/"Moon pi” is another “pi(e)” joke.

Wikipedia: Pi
The number π is a mathematical constant, the ratio of a circle’s circumference to its diameter, commonly approximated as 3.14159. It has been represented by the Greek letter “π” since the mid-18th century, though it is also sometimes spelled out as “pi” (/paɪ/).

Final Jokes (Some Raunchy and Some Political) from James
James D. Milton
11/1/98
“Halloween Q & A”
(...)
Q: What do you get when you divide the circumference of a jack-o-lantern by its diameter?
A: Pumpkin pi

Ann: Science Jokes updated
Dave Bostock
11/4/99
A possible addition that I observed in a Holloween post of rec.humor if not already in the Sci. list.

What do you get when you divide the circumference of a pumpkin by it’s diameter ? .... drum roll ... pause ...  more drum roll ...

pumpkin pi

Daily Devotional 10/31/00 Tuesday
Shirley Lin
10/31/00
(...)
What do you get if you divide the circumference of a jack-o-lantern by it’s diameter? Pumpkin pi

One Man’s Journey Through Mathematics
By Marvin L. Bittinger
2004
Pg. 108:
What do you get if you divide the circumference of a jack-o-lantern by its diameter?
Pumpkin pi.

The World’s Greatest Wacky One-Line Jokes
By Bob Phillips
Eugene, OR: Harvest House Publishers
2005
Pg. 86:
What do you get if you divide the circumference of a pumpkin by its diameter?
Pumpkin pi.

matt lambert
‏@mattlambert
Teacher: What do you get if you divide the circumference of a pumpkin by its diameter?
Student: Pumpkin pi.
2:52 AM - 18 Feb 2008

The Mammoth Book of One-Liners
By Geoff Tibballs
London: Constable & Robinson Ltd.
2012
Pg. ?:
What do you get if you divide the circumference of a pumpkin by its diameter?
Pumpkin pi.