russian translation

I suspect there's been some kind of mistake. There is no common Russian word третка (tretka); that combination of letters gets less than 100 hits, total, on Google, most referring to an extremely obscure forestry term.

Are you sure your friend didn't intend тётка (= "Auntie") or some other word with a similar spelling? It would help to know the general subject of the letter. At any rate, it seems probable a typo was involved.

at first i thought it could be аткрытка,but it is too different from that.

Was it printed? Or was it written in script? If the latter, what about клетка? Depending on the person's handwriting and the recipient's interpretation, a script capital T and a capital K might be confused because of all the flourishes, and a script lower-case L could be mistaken for a lower-case R in the Roman alphabet. I'm grasping at straws, obviously.

NA - "subject header" sounds like an email, so it's unlikely to be a handwriting issue.

NA - "subject header" sounds like an email, so it's unlikely to be a handwriting issue.

So you're telling me I went through all those mental gymnastics for nothing? Darn!

hey, buddy, you have to stay in shape!

It seems to be a common Czech word meaning "trinket."

@7 - cognate to Yiddish tchotchke? (hard to transliterate, sorry)

wiki doesn't have a Czech cognate for tschotschke, but the Slovak is čačka, and I imagine the Czech cognate is close to that, if such a word exists in Czech. Tretka looks too different to be from the same root.