“Do you want to hear a construction joke?”/“I’m working on it.”

The construction industry has a joke that’s told about it:
 
“Do you want to hear a construction joke? Sorry, It’m still working on it.”
 
The joke has been cited in print since at least 2004.
 
 
Google Groups: alt.humor.puns
Kids Puns of the Weak 05-25-04
Stan Kegel
5/25/04
(...)
Do you want to hear a construction joke?
Sorry, I’m still working on it! (Horace, 17)
   
Google Books
ROFL:
Rolling On the Floor Laughing Joke Book
By Tangerine Press and Sarah Perez
New York, NY: Tangerine Press
2005
Pg. 207:
Do you want to hear a construction joke?
Sorry, I’m still working on it.
 
Boston (MA) Globe
Q & A
Sydney Stoll
By Zach Hosseini, Globe Correspondent |  October 25, 2005
(...)
Q. What’s the worst joke you know?
A. Do you want to hear a construction joke? Hold on, I’m working on it.
 
Google Books
December 2008, Boys’ Life, “Think & Grin,” pg. 60, col. 2:
Bob: Do you want to hear a construction joke?
Tom: Sure!
Bob: Sorry, I’m still working on it.
Isaac Brown, Arden, N.C.
   
Twitter
Adam
‏@pranksta06
Let me tell you guys a construction joke…....... well, I’m still working on it….
12:35 AM - 20 Apr 2011
 
Twitter
A. Dreamer.
‏@Beeros75
want to hear a construction joke? I’m working on it @iamsrk
4:27 AM - 25 Jul 2014