“What did one traffic light say to the other traffic light?” (joke)

A traffic light joke is:
 
Q: What did one traffic light say to the other traffic light?
A: “Don’t look! I’m changing!”
 
The joke has been cited in print since at least 1993.
 
“Why did the traffic light turn red?” is another form of the joke.
       
 
Google Groups: rec.humor
What did say to the other?
Ian Metzke
8/4/93
what did one traffic light say to the other?
don’t look now I am changing.
     
Google Books
Wacky Wheelies:
A Book of Transportation Jokes
By Mark Ziegler
Illustrated by Anne Haberstroh
Minneapolis, MN: Picture Window Books
2005
Pg. 6:
What did one traffic light say to the other?
“Don’t watch me while I’m changing.”
 
Twitter
Lupe Lopez
‏@lupelopez09
@kinagrannis what did the traffic light say to the other traffic light? ... “dont look im changing” >.<

1:06 PM - 17 Dec 2009
 
Facebook
Clean Funny Jokes
December 2, 2012 ·
What did one traffic light say to the other?
Don’t look I’m changing!
   
Google Books
More One Liners,
Jokes and Gags
Compiled by Grant Tucker
London: The Robson Press
2013
Pg. ?:
What did one traffic light say to the other traffic light? ‘Don’t look! I’m changing!’
 
reddit
what did the traffic light say to the other traffic light?
submitted June 24, 2016 by franktdt
Don’t look i’m changing