“What’s long and thin, covered in skin, red in parts and goes in tarts?”/“Rhubarb.”

A food riddle—with sexual innuendo—is:
 
Q: What’s long and thin, covered in skin, red in parts, and goes in tarts?
A: Rhubarb.
 
The riddle has been cited in print since at least 1974.
 
   
Wikipedia: Rhubarb
Rhubarb (Rheum rhabarbarum) is a species of plant in the family Polygonaceae. It is a herbaceous perennial growing from short, thick rhizomes. It produces large poisonous leaves that are somewhat triangular, with long fleshy edible stalks and small flowers grouped in large compound leafy greenish-white to rose-red inflorescences.
 
In culinary use, fresh raw leaf stalks (petioles) are crisp (similar to celery) with a strong, tart taste. Although rhubarb is not a true fruit, in the kitchen it is usually prepared as if it were. Most commonly, the stalks are cooked with sugar and used in pies, crumbles and other desserts.
         
Google Books
Semiotica
Volume 10
1974
Pg. 161:
What’s long and thin
And covered in skin
Red in parts
Shoved in tarts?
Answer: “Rhubarb.”
 
Google Books
Captain Cook Chased a Chook:
Children’s Folklore in Australia
By une Factor
New York, NY: Viking Penguin
1988
Pg. 165:
An example is given by the Opies to illustrate their contention that we must be aware of the context in which verbal lore is transmitted in order to evaluate it accurately:
 
Q. What’s long and thin, Covered in skin, Red in parts, And goes in tarts?
A. Rhubarb.
 
Google Books
Last Night Another Soldier
By Alistair Renwick
Information on Ireland
1989
Pg. 153:
‘Okay, what’s long and thin, it’s covered in skin, it’s red in parts, and you shove it into tarts?’
 
The women looked away in disgust.
 
‘There you are, they’ve got real dirty minds,’ said Corporal Bruce. ‘The answer is — a stick of rhubarb,’ he shouted.
 
Google Groups: eunet.jokes
REQUEST: body builder jokes
E’ Cunningham
10/5/93
(...)
OBJOKE (From Radio 1 early morning show): What’s long and thin, pink, covered in skin and goes in tarts?
 
Rhubarb.
 
Google Groups: aus.jokes
It’s long and thinand covered in skin
.(JavaScript must be enabled to view this email address)
3/26/96
It’s long and thin
It’s covered in skin
It’s pink in parts
I put it in tarts
Read this carefully
Rhubarb you’ll find
Not what you’re thinking
That’s your dirty mind
Tonxi
 
Google Groups: rec.humor
Re; Long and thin
Martyn Kershaw
7/16/97
Gloria Burnett wrote:
>
> Albert Blais wrote:
> >
> > Albert Wrote:
> >
> >      Hey, whats long and thin and covered with skin and been through
> > may holes?
> AN EARTH WORM
 
OR:
Long and thin,
Covered in skin.
Red in parts,
Put in tarts.
 
What is it?  Rhubarb!
   
Twitter
In Demand Music
‏@indemandmusic
Dave Lloyd-jones whats long , thin , covered in skin , red in parts and goes in tarts ?????....................... http://tinyurl.com/dhrfuc
5:59 AM - 12 Mar 2009
 
Twitter
George Docherty
‏@Hawkeye_The_Noo
Q: whats long & thin, covered in skin, red in parts & goes in tarts?? A: RHUBARB of course - u dirty little buggers! Honestly!
4:58 AM - 27 May 2009
 
Google Books
Unriddling the Exeter Riddles
By Patrick J. Murphy
University Park, PA: The Pennsylvania State University Press
2011
Pg. 227:
In an offhand footnote, Barley remarks, ‘‘I have recently come across a modern parallel to this sort of riddle in the form: ‘What’s long and thin / And covered in skin / Red in parts / Shoved in tarts? / Answer: ‘‘Rhubarb.’‘’
 
Twitter
Shit Jokes
‏@ShitJokes
What’s long and thin…
Covered in skin…
Red in parts…
and goes in tarts?...
Rhubarb
3:38 PM - 15 Jan 2017