“Little Johnny: Teacher, can I go to the bathroom?” (joke)

A school classroom joke has been printed on several images:
 
LITTLE JOHNNY: Teacher, can I go to the bathroom?
TEACHER: Little Johnny, MAY I go to the bathroom?
LITTLE JOHNNY: But I asked first!
         
The “can I”/“may I” grammar joke has been cited in print since at least 2004.
 
     
Meddhy
MAR/02/04 ♪
Little Johnny: Teacher, can I go to the bathroom?
Teacher: Little Johnny, MAY I go to the bathroom?
Little Johnny: But I asked first!
 
Google Groups: SidsW0rld
Sms Jokes
Rochelle Miranda
6/12/06
(...)
Little Ria: Teacher, can I go to the bathroom?
Teacher: Ria, MAY I go to the bathroom?
Little Ria: But I asked first!
 
14 January 2007, Toronto (ON) Star, “We have the answer to your school daze dilemma. Your assignment is to read these classroom funnies!,” pg. C20:
Little Lou Teacher! Teacher! Can I go to the bathroom?
Teacher Lou! Lou! May I go to the bathroom?
Little Lou But teacher I asked first. 
 
20 May 2008, The Daily Mirror (London, UK), “Greg’s giggle,” pg. 42:
‘LITTLE Johnny puts his hand up in the classroom: “Teacher, can I go to the bathroom?” Teacher replies sternly: “Little Johnny, MAY I go to the bathroom.” Little Johnny pleads: “But I asked first!”
     
Google Books
English Jokes for ESL Students
By Gladys Garcìa Fernández
Lulu Press (Lulu.com)
2009
Pg. 23:
Little Johnny: Teacher, can I go to the bathroom?
Teacher: Little Johnny, MAY I go to the bathroom?
Little Johnny: But I asked first!
 
Google Books
Tom, Dick, and Harley
By James Albert
Indianapolis, IN: Dog Ear Publishing
2015
Pg. 183:
HARLEY, Jr. Can I go to the bathroom?
TEACHER MAY I go to the bathroom!
HARLEY, Jr. I asked first.
   
Reddit—Jokes
Teacher, can I go to the bathroom?
submitted May 26, 2017 by ericand
Little Johnny: Teacher, can I go to the bathroom? Teacher: Little Johnny, MAY I go to the bathroom? Little Johnny: But I asked first!
 
Reddit—Jokes
Little Johnny: Teacher, can I go to the bathroom?
submitted February 21, 2018 by SuperFunBaby
Teacher: Little Johnny, MAY I go to the bathroom? Little Johnny: But I asked first!