"I want to tell you something very important."
Translation:Chcę wam powiedzieć coś bardzo ważnego.
In such a construction, "coś" takes a form ending with -ego. I think it's neuter Genitive.
Accusative – genitive would be „czegoś bardzo ważnego”(cf. „Słucham czegoś bardzo ważnego”); It also changes to genitive in negations, as would be the rule:
- „Nie powiem ci czegoś bardzo ważnego”(through that's a bit stilted example, I would rather say „Nie powiem ci niczego ważnego” normally, even if it's not the same meaning 100%)
Good point, but if it's Accusative, then it's also not really neuter (that would be "ważne") but masculine (for whatever logic). The most important thing is still "it ends with -ego" :)
Generally "coś" is neuter, you can say "jakieś dziwne zielone coś" (some weird green something).