Fat and slim are opposites. Make it make sense.

Not a native speaker, but I always interpreted fat chance to have an ironic undertone. So... literally it'd mean the opposite, but it's never used literally.

Those expressions are stupid anyway. Say high/low probability instead.

According to this stackexchange:

fat chance is like a cynical no chance:

You think you can win the lottery? Fat Chance.

slim chance is when there is a small possibility. It does not infer any hidden meaning.

Even though I did not study, there is a slim chance that I will pass the test.

The phrase "fat chance" was likely originally used sarcastically. A quick search doesn't show any consensus, though.

Slim chance is the objective way of expressing a low likelihood. Fat chance is a colloquial expression using irony. You say one thing but mean the opposite. It's more often used as just a quippy two-word reply.

Language doesn't make sense. When flammable and inflammable can mean the same thing, all bets are off. You cannot make sense of these things; you can only accept them.

I read it this way too. It's like how your biggest friend might be nicknamed Tiny

I don't know that you can pin down the origin, but a quick search suggests it was early 20th century American English. That makes sense to me, it sounds like the sort of slang I'd hear in an old gangster movie

If you updated the slang for modern times I don't know if it would have the same impact. If somebody told me I had a dummy thick chance, I'd think my odds are pretty good

∆__ this guy Spocks

Likewise, “all but impossible” sounds like the probability is anywhere above zero (0, 1]. Counterintuitively, what it really means is that it is actually very close to zero. So maybe something like [0, 0.1]. Should zero be included in this interval?

I could care less about this

They're not the same though. "Fat" chance carries lard/tallow which can burn, so it is flammable. "Slim" chance has no lards or greases to burn, therefore it is "inflammable". /s

You could, but apparently don’t.

I mean it still is used sarcastically, even if the user might not be aware of it.

wooosh?

Plus language evolves organically and isn't always perfectly logical and consistent.

Because English is three languages in a trench coat pretending to be one language.

"fat" ain't "good", brah. you gotta say "t h i c c"~

jokes aside, it's mostly answered by other good comments here.

I think "fat" is sarcastic. At least that's how it reads to me.

They don't mean the same thing as I understand them. Slim chance means there's a chance but fat chance means practically no chance.

You want me to use a 5 syllable word when a 1 syllable word will do? Fat chance!

Thanks!

Who knows really. Take it literally, and they probably care quite a bit. If not, the amount of caring is exactly zero.

You can't buy bread with syllables, no need to save them :)

So you care a lot?

Fat chance is sarcastic, slim chance is direct

Irregardless, it's confusing when opposites mean the same thing.

Never tell me the odds.

Odds

because the persons who came up with those phrases were Biggie Smalls and FatBoy Slim

Not the origin of this. We can't just say that to everything related to English.

They dont.

"Are you up for it?" and "Are you down for it?" both mean the same thing too

Not sure if against the rules, but you're a stuck-up, half-witted, scruffy-looking nerfherder.

Things can burn up and down at the same time.

🎵Biggie Smalls is celibate in hell, celibate in hell, celibate in hell 🎵

Yeah, no.

......what? No, sorry, I was offering another example, not replying to your salient point. ;-)

Depends on context. "Slim chance" might technically allow for a small chance, but a lot of the time it's used, it's used to indicate that the speaker considers there to be no actual chance. Like if you say "That's probably not gonna work" you probably actually mean "I believe that is going to not work".

But this discussion is interesting, because I'd imagine "fat chance" only came about as a sarcastic way of saying slim/no chance. I'm pretty sure it's like "disgruntled" where nobody is actually gruntled. Language is delightful. :)

Of course you can say that. It'd be wrong, but you absolutely could say it. ;-)

I'm only upvoting you through my narrowed eyes because I hate you so much. lol

That ones slightly different though, because that "yeah" means "OK" or "uh", not "yes" in this context. Its just a way to give your brain extra time to think of a response.

pedantic, yes, but I enjoy that

Wait until you find out a grill utensil is called a spatula but a tool to mix baking ingredients is also called a spatula.

This is how I felt when I tried to win an argument about 'deceptively deep' and found that usage was subjective and that 'deceptively shallow' could be used interchangeably

Fat chance is ironic, slim chance is not. it's just that nobody uses fat chance in a non sarcastic manner.

Gotta get up to get down

Yes, for all intensive purposes.

Sort of--but given that "fat chance" really only has one meaning today, I wouldn't call it sarcasm really. For sarcasm, I think it would have to be able to be interpreted two different ways.

Fat Chance is pretty much always sarcastic. However most other common sarcastic phrases are also used sincerely, so it's actually kind of unique. You could say Phat Chance though which would probably be sincere.

That's why I call the grill one a lifter. I work in an English speaking kitchen in a non English speaking country, so a lot of my coworkers believe me on things like this. I am also trying to get them to say pasghetti.

A fat chance means the odds are so wide it would be impossible. Like, you have so many slim chances at once on different factors for it to remotely work.

A slim chance means the odds are tight but there is an actual chance on a single factor.

One slim chance is better than 40 slim chances focused on a single goal, so fat chance.

When I use slim chance, I actually will try it if it isn't going to work and it wouldn't hurt to try.

Fat chance means you shouldn't bother to try it. The stars would have to perfectly align.

Fat and slim are both as far from the middle of the Gaussian;