Just what is this RIS that some of you speak of?
and don't do the let me google that for you thing please.
( fuck shit up the best you never had, Thu 30 Apr 2009, 20:49, 10 replies, latest was 16 years ago)

My understanding is it came from an illuminated Morrisons sign that had the letters 'RIS' unlit, leaving the word MORON.

Hence if you dont understand, or something needs to be explained... RIS... for morons.
( enoughblueskyforsailorstrousers, Thu 30 Apr 2009, 20:52, Reply)

The key being
that someone saw the picture and said 'RIS? I don't get it' much to the amusement of /board

And it stuck.

Edit: and the eternally resourceful mictoboy spake it thus:

dictionary.mictoboy.co.uk/define/RIS/

Edit 2: and lo! b3ta did offer the post for consumption:

www.b3ta.com/board/4890991
( Noeli overtheshoulderboulderholderthingstraplatchboobs, Thu 30 Apr 2009, 20:54, Reply)

RIS?
*dies due to level of my own funniness*
( Devil_In_Tights the *real* DiT!, Thu 30 Apr 2009, 20:54, Reply)

Not quite.
It started out with an unshopped photo that someone posted of a Morrisons where the "ris" had burned out, resulting in it saying "Morons". Almost immediately two people thought at the same time that he was trying to write "RIS" in black letters, and posted "RIS? I don't get it."

Now RIS means "I don't get it". To de-ris is to provide an explanation.

EDIT: I was trying to respond to ancrenne. Sorry.
( The Resident Loon Not a demographic. Do not measure., Thu 30 Apr 2009, 20:55, Reply)

Thank you kindly folk
so then to say it in context would imply that I'm a moron. Must choose usage carefully.
( fuck shit up the best you never had, Thu 30 Apr 2009, 21:01, Reply)

No.
To say it in context is to imply that you don't get it and would like an explanation.
( The Resident Loon Not a demographic. Do not measure., Thu 30 Apr 2009, 21:07, Reply)

Ergo I'm a moron as I don't get it
Edit: As in I feel like a moron as I don't understand what the post is about or what is being implied in that situation.
( fuck shit up the best you never had, Thu 30 Apr 2009, 21:33, Reply)

It means that if somebody writes something you don't understand,
you can respond: RIS?
This is another way of saying: I don't get it.
( thealternativefact, Thu 30 Apr 2009, 21:36, Reply)