“Puns about monorails always make for decent one-liners”

A monorail pun is:
 
“Puns about monorails always make for decent one-liners.”
 
The joke was posted on Twitter on October 6, 2010 and probably originated on the website Pun of the Day.
   
   
Wikipedia: Monorail
A monorail is a railway in which the track consists of a single rail. The term is also used to describe the beam of the system, or the vehicles traveling on such a beam or track. The term originates from joining “mono” (one) and “rail” (rail), from 1897, possibly from German engineer Eugen Langen, who called an elevated railway system with wagons suspended the Eugen Langen One-railed Suspension Tramway (Einschieniges Hängebahnsystem Eugen Langen).
     
Twitter
Terry Johnson
‏@Green4Power
Puns about monorails always make for decent one-liners.[Click to Vote!]  - lol
2:16 AM - 6 Oct 2010
 
Google Groups: Fed2 Star
Fed2 Star - October 10, 2010 - page 3 (of 3)
Fi Craig
10/10/10
(...)
Stardate: 128637:6933 - Occy: Puns about monorails always make for decent one-liners
   
21 October 2010, The Sun (London, UK), “Have a laugh!,” pg. 33:
PUNS about monorails always make for decent one-liners.
 
Twitter
PUNS
‏@omgthatspunny
Puns about monorails always make for decent one-liners.
8:07 PM - 27 Jul 2012
   
2 October 2013, The Sun ((London, UK), “Daily Smile LOL,” pg. 19:
A BIG large shout out for tautology. PUNS about monorails make for decent one-liners.
   
BuzzFeed
How Punny Are You, Actually?
So you think you’re tons of pun? GEICO has a good list you should probably check.
posted on Apr. 29, 2014, at 5:08 p.m.
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6 Puns about monorails always make for decent one-liners.
 
FASAB (Fight Against Stupidity And Bureaucracy
Puns About Monorails Always Make For Decent One-Liners.
April 30, 2015