“What do you call a teacher who doesn’t fart in public?”/“A private tooter.”

There’s a joke about private tutors:
 
Q: What do you call a teacher who doesn’t fart in public?
A: A private tootor.
 
The pun began as a musical joke. “WHEN is an educational instructor like an amateur flute player?—When he’s a private tooter” was cited in a humor magazine from 1870.
 
“What do you call a guy who never farts in public? A private tooter” was in a 2003 joke book. “What do you call a teacher who only farts at home? (A private tooter)” was cited on Twitter on May 26, 2009.
 
“What do you call a temporary teacher fart?”/“A substitoot” is a related joke.
 
   
Google Books
2 March 1870, Judy, or the London Serio-comic Journal, pg. 181, col. 2:
WHEN is an educational instructor like an amateur flute player?—When he’s a private tooter.
 
Chronicling America
28 November 1878, Mexico (MO) Weekly Ledger, “Wit and Humor,” pg. 4, col. 2:
A private tooter: A recruit who plays the trombone.
(Reprinted from the Chicago Daily Tribune of November 10, 1878.—ed.)
 
Google Groups: rec.audio.pro
The Unspoken
Dave Martin
4/3/00
(...)
So instead of farting in public, you’re a ‘private tooter’?
 
Google Books
A Prairie Home Companion
Pretty Good Joke Book
By Brian Becker
Minneapolis, MN: HighBridge
2003
Pg. 65:
What do you call a guy who never farts in public?
A private tooter.
 
Twitter
Agile Cruz
‏@agilecruz
What do you call a person who never farts in public?  ..........a private tooter. .....Come on!  That’s funny!  I don’t care who you are…
8:32 PM - 5 Dec 2008
 
Twitter
Slade
‏@OldManSlade
@ddlovato What do you call a teacher who only farts at home?                    (A private tooter)
9:42 PM - 26 May 2009
 
Twitter
Vikki
‏@vikkiz0rz
What do you call a teacher who never passes gas in public? A private tooter! HAHAHAHA oh man
12:58 PM - 30 Jun 2009
 
Twitter
Victoria Carlson
‏@VmCarlson7
#Joke of the day: “What do you call a teacher who doesn’t fart in public?” Answer: “A private tooter” 😊
12:16 PM - 29 Jan 2012
 
reddit
What do you call a teacher that doesn’t fart in public? (self.Jokes)
submitted October 14, 2015 by KentieBoy
A private tooter
 
reddit
What do you call a teacher that doesn’t fart in public? (self.Jokes)
submitted February 26, 2016 by atodaso
a private tooter.