The thing of it is is...
I heard this English idiom spoken quite often, with two consecutive occurrences of "is", -- example:
The thing of it is is that John didn't want to go out with Mary.
It means,
The most important fact is that John ...
I believe it is valid grammar, but I find it annoying. When you google the expression "the thing of it is is that", you find 1,830,000 results!!!
Also annoying is a related expression,
What it is, is ...
What do you think? Do students of English need to learn about this? It's not too difficult, but I suppose it is bad style.
Here's a funny statement one forum member on languagehat.com wrote about it:
The thing of it is is that the thing 'the thing is is' is is what the thing 'the thing is is' is was and what the thing 'the thing is is' is will be, things the thing is is are being what things the thing is is are are.
I have not yet decided if it even makes sense 
17 Answers
I have not heard , " the thing of it is" but it is common to say,"the thing is "
and then one goes on to explain a point. What it is , is this, also is quite common
in speech when one is explaining something . Remember that ,is, is a very powerful
word, what isthat how "is" that , it "is" , " is " he , where " is "it , and so on ,
It cannot be overdone although it looks awkward ,is, is correct.
I love it!
What it is is...
That's standard fare in my region. A great way to answer a question that starts off "What is...?"
However, "the thing of it is is..." sounds really odd. Here, we say "the thing is is..." which is much better.
I was going to visit my uncle today. The thing is is I have to work today.
What's a buffet? What it is is a bar in a restaurant where you serve yourself.
It's important to note that the two is's are said with very different emphasis.
Grammatically, these are merely noun clauses. In other words, the whole clause is acting as a single noun grammatically. "What it is" can usually be replaced simply with "it".
Spanish can do it, too, I'm sure...
Qué es eso?
Lo que es es....
I don't know if they would do that, though.
The thing of it is is that the thing 'the thing is is' is is what the thing 'the thing is is' is was and what the thing 'the thing is is' is will be, things the thing is is are being what things the thing is is are are.
Omg I find this very hard to understand!! The thing is is this expression is very annoying!!
Funny this subject should come up. I just heard "the thing that it was, was "on a British comedy program on t.v. But I can't say that I've heard "the thing of it is" before.
The Bu(r)ffet Song by Rhett and Link has a nice example of "what it is is..." in it.
It's also got a bastardized version of the somewhat vulgar idiom "out the wazoo" (wazoo is a euphemism for anus), which basically means you've had so much of something that you're sick of it...a lady in the video gets the saying wrong and instead says "up the kazoo."
(A kazoo is pictured below.)
Que será,será.
The thing of it is is that John didn't want to go out with Mary.
I am basically in agreement with the others, this is not good grammar. A more correct way of saying this would be The thing is, John did't want to go out with Mary.
You can get occasions where the same word occurs twice but usually there is a pause in speech, or a comma in writing, which really helps tp clarify the meaning.
Hmm, never heard this before, and trust me, our friend Chris has the weirdest English grammar on the forum! 
I often say: the thing is that...the thing is...
According to my sister, who has been an editor for 42 years these frazes are acceptible in spoken language but un acceptible in the written language. She was horrified to find out that it was used in a leagal brief.
I'd say
1) "The thing is....(pause)....John didn't want to go out with Mary.
I have also heard:
2) The thing of it is, (pause) is that John didn't want to go out with Mary.
I prefer #1.
I don't know whether it is correct grammatically, but what I would say is...... "The thing about it is, (pause) John didn't want to go out with Mary"
Yuk that sounds horrible to me!
I dislike overuse of 'thing', Also, like Ray I've mostly heard "The thing is", not "The thing of it is".
In my opinion (and I'm careful to start my sentence with those 3 words ;P) it's preferable to say "The fact of the matter is", or "The case is" such-and-such.
The double 'is is' is wrong. Only one 'is' is required. The only time a double 'is' would be appropriate would be in
'What it is, is ...'
and even this is clumsy.
It is correct English. There are a number of phrases that have repeated words like "is is", "that that", "had had", etc. that many people strive to avoid because even though they are correct, they sound bad.
As for a legal setting, I'd be less surprised to hear: "Your Honor, I move for a 30 minute recess so my client can be chillin' wid 'iz homeys."
There was a thread over a year ago that showed how to construct a sentence with arbitrarily many "that"s in a row.
Pesta, I have never heard the "is is" used. Is this a regional convention? I can't believe it is is correct grammar.
