“La rumeur dit vrai : The Last Face est une daube de proportion
cataclysmique. L’un des plus gros foirages qu’il nous ait été donné de
voir depuis l’invention du ralenti. C’est aussi un film indécent, qui se sert des guerres au Liberia et au
Soudan du Sud comme moteur aphrodisiaque d’une bluette où l’on regarde,
médusés, se débattre les malheureux Javier Bardem et Charlize Theron
comme des mouches dans une flaque de sang, alors qu’un énième mouvement
de caméra tourbillonnant nous fait tendre le bras vers le sac à vomi” (http://next.liberation.fr/cinema/2016/05/20/the-last-face-l-indecent-drame-de-sean-penn_1454074)
Ah ah, that’s totally slang. Don’t worry if you don’t find it in a dictionary, I’m pretty sure this word doesn’t even exist.
“Foirer” is a slang verb that means “to make a big mistake” (there are probably better equivalent, like “to f*ck up”, but “foirer” doesn’t sound that vulgar). A “foirage” would just be “a big mistake”, except it really feels stronger than just “a big mistake”. You would have to add a bit of contempt and of vulgarity to get the real meaning, I think.
I can read and understand (almost) everything (grandmothers taught me French, and that from the very inception of my life ), but unfortunately lately I am forgetting a lot, I don’t use it anymore…I would not trust myself to send an email longer than 5 lines nowadays
And now what? so “foirage” is popular among very young people both in France and in Belgium? I am not sure if I ever heard it - or … probably I did, but… as I could not “locate” it, I probably “overheard” it…
Well, now what, that’s up to you
At least you know what it means now.
Still, not sure it’s only among very young people, at least not where I’m from. I could very well hear someone over 50 say that, as long as it is not in a formal setting (news broadcasters and the like). In the local bar for instance. In popular movies, too. Well, after all, it’s slang, so can’t really generalize anything.
My take on it is that ‘foirage’ is a form you don’t see/hear very often (it’s sort of an ‘elegant variation’…), but that people do often use the verb form ‘foirer’ and the adjective form ‘foireux/foireuse’. I don’t see it as restricted to any particular age group.
The adjective’s really useful in daily life when you come up against (yet another) ‘plan foireux’ that’s doomed to failure or obviously going to descend into chaos and/or waste a huge amount of time.
And you might need it to be able to say about a proposal, idea, approach, ‘Elle est complètement foireuse!’, or ‘Elle est complètement foireuse, celle-là!’; or for a system, a nonsensical example or a badly-designed device, ‘Il est complètement foireux’ / ‘Il est complètement foireux, celui-là!’
You can also use these of a man or woman who’s wildly disorganised or one who constantly loses things, or is accident-prone because of all of this, or someone who is doing/saying things that don’t make sense. While slang and very informal, it can be either relatively neutral/affectionate/humorous, or quite pejorative (from just dismissive through to contemptuous), so it also works when someone is doing nonsensical/obstructive things with malicious intent to stir up a situation or to hinder someone else. Among other exasperated or rude things you could say to describe that!
Or when commenting, in a neutral structure, you can say ‘C’est complètement foireux’ (I saw that used online here, for example: “Trump essaye de se réconcilier avec les latino-américains mais c’est complètement foireux”)
But I would also often replace foireux/foireuse with ‘C’est du n’importe quoi’, which is another very useful expression, or ‘Il/elle fait n’importe quoi’
You could maybe replace ‘foirage’ in the example of the uncomplimentary film review with ‘cafouiilage’ or ‘ratage’…
Am I considered to be the “young asset” to this conversation now?
I would definitely use “déconner”, “foirer”, “planter”, or “délirer”, that is not on your list. Oh, or “craquer”, as in “ils ont complètement craqué avec leur film” to put it back in context. But for the last two, the meaning is a bit different, it’s closer to “déconner” than “foirer”…
I can’t believe we are actually having this conversation. Language learning can be quite funny.
" Okie dokie"! (I tought I don’t understand the world anymore - which is true, I don’t, not really Sorry for the silly mistakes and typos. Keyboard is danish this evening)
edit: @sircemloud :I’d like to add “slang” as tag for this thread, but I seem unable to. Can you do it?
Don’t worry if you don’t find it in a dictionary, I’m pretty sure this word doesn’t even exist.
), but unfortunately lately I am forgetting a lot, I don’t use it anymore…I would not trust myself to send an email longer than 5 lines nowadays 
… thanks…
I find it interesting and funny