“Teacher: Why are you late? Student: Class started before I got here.”

A school joke is:
 
Teacher: Why are you late?
Student: Class started before I got here.
   
The student offers no explanation for lateness, but defines what lateness is. The joke has been cited in print since at least 1919.
   
     
Newspapers.com
9 December 1919, The High School Herald (Howard, KS), pg. 6, col. 4:
Mr. Hunt—And why are you late?
Freshman—Because the class had started before I got here.
 
Newspapers.com
3 February 1921, Westmoreland (KS) Recorder, pg. 8, col. 3:
Teacher—“Wendell, why were you late this morning?”
Wendell—Class started before I got here.”
 
Newspapers.com
8 December 1922, Republican-Register (Washington, KS), sec. 4, pg. 4, col. 2:
Jokes
Mr. Meyer: “Why were you late?”
Paul Swan: “Class started before I got here.”
 
Reddit—Funny
Posted by u/[deleted] October 18, 2011
Smart Kids
TEACHER: Why are you late? STUDENT: Class started before I got here.
       
Google Books
All Kinds of Humor:
Jokes, Quips, and Fun Stuff for Many
By Frank Verano
Xlibris Corporation (Xlibris.com)
2012
Pg. 679:
Teacher: Why are you late?
Pupil: Class started before I got here.
 
Twitter
E Gross
@shereesparks12
Teacher: Why are you late? Student: Class started before I got here.  21
4:03 PM · Jan 28, 2016·Twitter Web Client
   
Google Books
Magical Management in the Classroom:
Using Humor to Speak Their Language
By Linda Marie Gilliam
Lanham, MD: Rowman & Littlefield
2019
Pg. XI:
Teacher: Why are you so late?
Student: Class started before I got here.
 
Twitter
Bob Kostic
@causticbob
Teacher: “Why are you late?”
Little Johnny: “Class started before I got here.”
6:55 PM · Aug 18, 2022·Twitter Web App