Translation - French-English - j'en ai ma claque

You can say "I'm fed up" without an object in English, but then what's "en"?

I was mistaking with meaning of "en" in the note I let in the comments (So I removed it, simply because "j'en" means "j'ai en moi"(I have inside me).

Then, about translating "j'en ai ma claque" with English "I'm fed up" is particularly true when you have a look to the meaning of this expression in the 19th century :
"Ici, la claque n'est pas simplement la gifle.
Au XIXe siècle, en avoir sa claque, c'était "être rassasié".
So that it particularly suits with someone who's "fed up"(at first degree) >>someone who ate enough, and cannot eat more than he already ate. Someone satiated with the food he ate...
>>SOURCE

"I'm fed up" has nothing to do with eating - is this about eating? If so, it should be "I'm full".

It is ok for the expression,(you can validate) I used both english and French already about the same meaning,("en avoir sa claque," and "to be fed up with" but if "to be fed up" has got nothing to do with food, how come that in my (I know it's an old one) dictionary, at the French word "rassasier", I have this definition : "to satiate" (de, with); être rassasié de : to be fed up with.
Then "nourrir"( and also "se nourrir" is "to feed" "to feed", "food", all these words have got a relationship with food (originaly)
is it just because you English add these two tiny letters ("u" and "p", making "up" that it hasn't anymore to do with it? the past participate is the same, would it be "fed up" or "fed" it comes from "to feed", doesn't it?

1) I am not English.

2) When you add "up" to "fed", it becomes an idiom which no longer has anything to do with food or feeding.

1) "English native speaker" (sorry!)

2) Always seemed strange to me, the way English language was displaid, with all these "up", "down", "on", "off", and a lot of other adds to the verbs that completely change the meaning of the basic verb or its past-participate.

For the French guy that I am, this is kind of confusing and hard to understand, it nearly seems to me as English were "biting the hand that feeds them"(LOL), forgetting the original meaning of the verb (though it is still included in the idiom, when you pronounce this idiom you also pronounce the original verb this idiom was made with.)
And without use of the verb in it, wouldn't make sense, this is why I used the expression above "to bite the hand that feeds you". And this is also because which I thought was logical to my French speaker mind didn't sound logical at all to you, I guess...

This is the nature of an idiom - that it changes the original meaning of the word. Please see this page.

But my question remains, because I'm not familiar with the French expression "j'en ai ma claque", is this translation correct? Is it about eating or not?

Germanic languages always use it, Francky.
"up", "down", "on", "off"

The french expression is the exact translation of the english one.("en avoir sa claque" = "to be fed up"
It had something to do with food in the 19th century (see link I provided in my 14 July 2007 11:56 post, but it nowadays doesn't have anything more to do with food.(We French also sometimes bite the hand that feeds us)

I submitted another one to translation into french, which is "to be fed up to the back teeth", and this would tell me wether this is "to be fed up...to the back teeth", or "to be fed...up to the back teeth"

(casper, 70% of the English vocabular comes from old French as well, even if English has Germanic origins, and if Germanic languages use this kind of specific idioms)

They use these auxiliary words to form new verbs and expressions.

I had always thought Northern languages were weird, just like you, Francky, but I suddenly realized we, Southern Latin Europeans, do the same thing, how? well:

on sous-entend
on par-court
on pour-voit
on dé-gage
on ré-fléchit
on sur-prend

Spanish, Italian, Portuguese, etc, work in the same way,

only, we use prefixes instead of separate words to change the whole sense of a verb.

We do that too. But every language has idioms, also.

I could figure out that too guilon, but I would never deny that in the word "sous-entend" you've got "entend", and the same for any of the 5 other examples you gave : in everyone of them, I can recognize the basic verb and its meaning.
What I'm thinking about, and which seems weird to me, is that kafetzou told me "fed up" had nothing to do with "fed". When you say a baby is "bottle fed", this means he is fed using a feeding bottle. Now let's take the same example using an "absurd reasoning" : you don't stop feeding the baby, and he has more than his dose of milk; you'll notice that any time you present the feeding bottle to him, baby turns his head aside because he doesn't want anymore milk. What would you say then? I guess you'd say : "well, baby is fed up with the feeding bottle"! (wouldn't you?)

No, you wouldn't. You would say that the baby is full and should not be fed anymore. You are probably right that the word was originally connected with having been fed too much, but it has lost this meaning. We never say it in connection with food anymore, except to mean that someone is tired of eating the same thing and frustrated about that.

But you're being very (linguistically) naïve to think that English is unique in this way. The idioms just "feel" more logical to you in French than in English.

Here's an example that English-speaking French learners always find very amusing: tomber dans les pommes - where are the apples? There aren't any, are there?

I didn't think english was unique with these kinds of idiomatic expressions, you may think I'm a lot more naive than I really am, I already knew what casper and guilon said,not having said it myself doesn't mean I didn't know it (it is naive to believe that!) then I'm happy to read you said I was "probably" right that the word WAS originally connected with having been fed too much, because it is precisely what I wanted to read from you. You could even admit it HAD some relationship with food, since it had some relationship with "having been fed". So I'm glad you said that, because it isn't like the "it has nothing to do with food" I could read in your (14 Juillet 2007 15:13) post above.

Well, yes it is, because "it has nothing to do with food" is in the present tense. Maybe I should have said, "It has nothing to do with food now, although it probably originally did."