This is to ask for the exact meaning of the expression You must be kidding. More precisely, is it supposed to be: (a) friendly, (b) antagonistic, or (c) neither one?

In French the answer to my question for the roughly equivalent expressions Tu plaisantes or Tu rigoles would definitely be (a) but, as we all know, faux-amis do exist.

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    PS Didier, I think "You must be joking" is more common today than "..kidding". However "Are you kidding?" is, I think, somewhat common. As is "You're joking?" Kif kif. In anger it is often extended, along the lines "You must be abso-fucking-lutely seriously no-shit totally kidding me?" It's extremely difficult to give you a sense of whether it is aggressive. It can go either way. I would say it is a fact you can certainly use it in the most friendly, positive, supportive way -- or in an aggressive way. I'd actually avoid using it unless you are very native, personally. – Fattie Jul 10 '11 at 11:21
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    An interesting further observation - the shorter less-grammatical versions tend to be less aggressive / happier. ("Yer joking?!" - hooray, everything is good.) The longer more-grammatical versions tend to be challenges, aggressive. ("You Must Be Kidding Me?" I am in disbelief at the results of a pregnancy test.) So, consider that aspect! – Fattie Jul 10 '11 at 11:24
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    @Joe: Thanks for your two comments. (But I should confess not knowing how to recognize that a native is (or is not) very native... :-)) – Did Jul 10 '11 at 11:41
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    tatouage......! – Fattie Jul 10 '11 at 16:03
  • Of course. I should have known... :-) – Did Jul 10 '11 at 16:55

You use "You must be kidding" in any situation where you might say "I'm surprised that you just said that." I should say that this phrase is usually used with a NEGATIVE surprise, but not always. In any case, it's very informal.

A: I've become a scientologist. B: You must be kidding!

A: What's 2 + 2? B: You must be kidding! 4.

A: I won the lottery! B: You must be kidding.

  • Thanks for the theoretical answer and for the examples. – Did Jul 9 '11 at 22:39

I wouldn't say it's friendly. It's rather an expression of anger, denial. Like:

Person A: I've seen your girlfriend with another man.
Person B: You must be kidding!

It is neither friendly, nor positive. The responder says that you must be kidding, because he's in denial of what you just said and is hoping that you are trying to be funny, although usually knowing you're not.

  • Thanks. Examples of situations where the locution arises are just what I need, I think. – Did Jul 9 '11 at 19:26

Joe Blow appears to be correct in suggesting that "you must be joking" is more common today than "you must be kidding." But far more common (since 1980) than either "must be kidding" or "must be joking" in the Google Books library is "got to be kidding" (sometimes spelled "gotta be kidding").

Here is an Ngram graph of "must be joking" versus "must be kidding" versus "got to be kidding" versus "gotta be kidding" for the period from 1900 to 2007:


The phrase "got to be joking" (not included in the above Ngram graph), by the way, seems to be less common than any of the four phrases in this Ngram graph—between half and two-thirds as common as "must be kidding" and "gotta be kidding" in the period between 2000 and 2007.

Does "you've got to be kidding" mean anything different from "you must be joking"? I don't think so. To my ear, though the former sounds more informal than the latter, it expresses the same combination of disbelief and a (possibly friendly) challenge to the hearer to clarify the previous statement, expand upon it, or admit that it wasn't intended seriously.

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    Thanks for the post. Your graph is amazing. It seems that a kind of phase transition occurred at some time around 1970 and I cannot help to wonder why. Or are there some different biases in Google Books library pre-1970 and post-1970? Or, or, or... :-) Anyway, thanks again. – Did Jun 25 '13 at 6:44
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    Maybe acceptance of relatively informal writing gained steam in mainstream publishing (not just in pulp fiction) during the 1960s—and "got to be kidding" rode the wave. But as you say, many other interpretations are possible. Perhaps some famous person used "You've got to be kidding me" as a catch phrase? In any case, the verb "kid" as slang for "josh, deceive, or make fun of" has been around for a long time. Wentworth & Flexner, Dictionary of American Slang (1960) point out this example from Eugene O'Neill's play The Hairy Ape (1922): "What yuh tryin' to do, kid me...?" – Sven Yargs Jun 25 '13 at 21:22

It is also used to oneself as an expression of exasperation and surprise "you have got to be kidding!", especially when the latest in a string of problems occurs.


Another unpleasant situation:

Person A asks a mathematical question, then Person B replies: “You must be kidding!” and gives the answer. I think Person B is implying that the answer was so simple that Person A should have known it without asking the question. In this context, saying “You must be kidding!” is like saying “You dummy!”

Now Person A could reply with a laugh by saying “D’oh! of course.” Or he could feel insulted at being called a dummy.

  • Or, "You must be kidding..." is like saying "You could not possibly fail to find the answer to this question unless you did not spend one minute thinking about it before asking". Anyway, it seems that "being called a dummy", if these words were not written by B, would be at best an extrapolation from A. – Did Jul 9 '11 at 19:21

protected by tchrist Feb 22 '15 at 4:46

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