“Why was the math teacher late for school?”/“He took the rhombus.”

The math term “rhombus” sounds like “wrong bus,” and there’s a pun:
 
Q: Why was the math teacher late for school?
A: He took the rhombus.
 
“Rhombus. Wrong bus?” was posted to the newsgroup alt.timewasters on January 12, 1999. “In Italy, I took a rhombus to get to the Vatican (Richard Lederer)” was in a “Puns of the Weak” post to the newsgroup alt.humor.puns on February 16, 2001. The math joke has been printed on several images.
     
   
Math Open Reference
Rhombus  plural: rhombi
Definition: A quadrilateral with all four sides equal in length.
     
Google Groups: alt.timewasters
Geometry
Judy Stephens
1/12/99
>>>>>>>>Everyones!  I take no sides. 
>>>>>>>How about angles?
>>>>>>Nope - I’m too square!
>>>>>I thought you were obtuse!            😊
>>>>No, I am running around in circles.
>>>Parallelogram?
>>Hypotenuse?  Pythagorean Theorem!
>
>Rhombus.
 
Wrong bus?  Hey, Taxi!
   
Google Groups: alt.humor.puns
“Puns of the Weak” 2/16/01
Stan Kegel
2/16/01
(...)
In Italy, I took a rhombus to get to the Vatican (Richard Lederer)
   
Wolf Pack W.O.W.
February 16, 2005
He Took the Rhombus
 
Twitter
Johnny Worthington
‏@jworthington
When visiting Italy last year, I got lost going to Florence and took the rhombus
10:04 PM - 22 Feb 2007
 
Twitter
DaveCon5
‏@dave_conklin
I was a gifted child; I took a rhombus to school.
8:56 PM - 22 Sep 2010
 
Twitter
Anna
‏@Markby
Why was the mathematician late for work? He took the rhombus.
3:42 PM - 12 May 2012
 
Twitter
Nerf Karate
‏@ManVsPuppet
Maybe you were such a nerdy kid you took a rhombus to school.
7:57 AM - 26 Oct 2013
 
Twitter
ワフラ ノマド マシャカ
‏@KiddyYusuf
Why was the mathematician late for work?
She took a rhombus
4:12 AM - 23 Jul 2014
 
Reddit
Why was the math teacher late for school?
submitted October 16, 2016 by shortsyaq
He took the rhombus