Куда уж тут: not likely!
At a dacha outside Moscow on a sunny afternoon, a group of friends are sitting around a table, telling байки (tall tales) and bragging about their financial acumen. You don't believe a word of it. So what do you say?
Thank goodness, you're all speaking Russian, which has a plethora of phrases and exclamations to express extreme doubt, refusal or absolute negation.
Let's say you're listening to a pitch to put your life savings in a no-risk, high-yield investment. The pitchman is your neighbor who has gone through three fortunes in 10 years and is occasionally visited by minions of either the mafia or law enforcement (so hard to tell the difference, they all dress alike). Your reply to the pitch? Ни за что! (Not for anything!) Ни в коем случае! (Under no circumstances!) Ни за какие деньги! (Not for all the money in the world!)
If Vasya-the-pitchman doesn't get the message, you can take a page from military jargon and insist: Никак нет! (In no way!) If he takes it as a joke coming from someone in civvies, you can try sputtering: Ни в какую! (Not for the world!). Or blurt out: Ни-ни-ни-ни-ни, which means: No, no, forget it, no way, man. Feel free to say ни as many times as you want — the more, the less merrier.
If that doesn't work, try using a word that in this context means "nothing": Фиг! (Zilch!) or Фиг от меня получишь! (You ain't getting nothing from me!) If Vasya's pitch has left you speechless, put your thumb between your index and middle fingers and wave it under his nose to convey: Zip. Zero. Nada.
Then there's the KamAZ-sized fish-that-got-away story. The problem is that you were in the boat and that little perch that wiggled off the hook definitely wasn't Jaws III. You can object politely: Ничего подобного! (Nothing of the sort!) Or you can point out that the story is false from start to finish: Нет ни капли or капельки (there isn't a drop), ни крошечки (not a grain), ни чуточки (not a bit) or ни крошки (not a crumb) правды (of truth).
If you want to assert that something — like truth — is totally missing from the story, you can use the charming phrase и не ночевало (literally, "and never even slept here"). The idea is that something is so not there, it didn't even pass through during the night. Наш начальник — честный?! В нашей фирме честность и не ночевала. (Our boss — honest? The company doesn't even know the meaning of the word!)
Or let's say one of your dacha-mates thinks his boss will give him a promotion, a raise and an extra week's vacation. You think this is as likely as pigs sprouting wings and flying around the office in pink tutus. In this case, you can use the curious expression куда там (literally, "to where there") or one of its variants: куда тут, куда уж, куда уж тут. They all mean: Too bad, but not likely.
You can also use куда by itself to express a kind of snorted negation:
"Скоро все сотрудники получат премию!"
"Куда получат! Денег нет у фирмы!"
("Soon all the employees are going to get bonuses."
"Like hell they are! The company doesn't have any money!")
And then you can add: чего нет, того нет (you can't squeeze blood from a stone).