“Double Gloucester” is a cheese, but it sounds like “double glossed her.” “I missed all that, ‘cos I was giving my sister two coats of paint. Yes, I double glossed her” is a cheese pun that was posted on the newsgroup alt.fan.pratchett on October 18, 2003.
 
This riddle form has been popular since at least 2011:
   
Q: How did the cheesemaker paint his wife?
A: He Double Gloucester.
 
   
Wikipedia: Gloucester cheese
Gloucester is a traditional, semi-hard cheese which has been made in Gloucestershire, England, since the 16th century, at one time made only with the milk of the once nearly extinct Gloucester cattle.
 
There are two types of Gloucester cheese: Single and Double; both are traditionally made from milk from Gloucestershire breed cows farmed within the English county of Gloucestershire.
 
Both types have a natural rind (outer layer) and a hard texture, but Single Gloucester is more crumbly, lighter in texture and lower in fat. Double Gloucester is allowed to age for longer periods than Single, and it has a stronger and more savoury flavour. It is also slightly firmer. The flower known as Lady’s Bedstraw (Galium verum), was responsible for the distinctively yellow colour of Double Gloucester Cheese. In the United Kingdom today, of these two types of cheese, it is the “Double Gloucester” which is more likely to be sold in supermarkets. Both types are produced in round shapes, but Double Gloucester rounds are larger. Traditionally whereas the Double Gloucester was a prized cheese comparable in quality to the best Cheddar or Cheshire, and was exported out of the County, Single Gloucester tended to be consumed within Gloucestershire.
       
Google Groups: alt.fan.pratchett
[C]heese (was Re: Birthdays!!!)
Daibhid Ceannaideach
10/18/03
(...)
I missed all that, ‘cos I was giving my sister two coats of paint. Yes, I double glossed her.
 
Twitter
Helen Macdonald‏
@HelenJMacdonald
RT @thescragend: How many times did the cheese paint his wife? He Double Gloucester. Profound apologies. (via @earlymodernjohn)
6:03 AM - 11 Jul 2011
 
Twitter
Stuart Aiken‏
@deltorro01
Why did the cheesemonger paint his wife twice? Because he Double Gloucester! http://on.fb.me/sBnbVT
8:03 AM - 30 Jan 2012
       
Higgypop
Ultimate List of Cheese Jokes & Puns
MARCH 1, 2013 12:52 AM
(...)
Q: How did the cheese man point his wife?
A: He Double Goucester.
 
Twitter   
Cheese Jokes‏
@dailycheesejoke
How did the cheese paint his wife? He double Gloucester
5:40 PM - 18 May 2014
 
The Sun (London, UK)
You’ve got to feel Perky when the Trotters are on TV
By TAM COWAN
25th September 2015, 7:55 am Updated: 5th April 2016, 11:14 pm
(...)
How did the cheesemaker paint his wife? He Double Gloucester!
   
Reddit—Jokes
How did Mr Cheese paint his wife?
submitted February 20, 2016 by barrbarian84
He Double Gloucester.
   
Twitter
Shit Jokes‏
@ShitJokes
How did the cheese paint his wife?
He double Gloucester
11:50 AM - 11 Oct 2016
   
Puns Ville
Cheese Puns
avril 20, 2017
The funniest cheese puns ever.
(...)
How did the cheese paint his wife? He double Gloucester.
     
Irish Times (Dublin, Ireland)
Is ice-cream the new pulled pork/doughnuts? It’s beginning to feel like it
Are We There Yet? Things to do with children this weekend
Fri, Nov 10, 2017, 21:46
Róisín Ingle
(...)
“How did the cheese maker paint his wife? He double glossed her” (Gloucester - it’s a cheese, see? Welcome to my world.)
 
Reddit—Jokes
How did the cheese-maker paint his wife?
submitted February 9, 2018 by SuperPonyRider
He Double Gloucester!