لب تر کردن

It depends on the boss. In a traditional Iranian office, it shows loyalty. In a modern international company, it might be too informal.

Usually no. It's almost always for favors, gifts, or help. You wouldn't say 'Wet your lips and I'll hit you.'

Yes, it is the closest English equivalent, but the Persian version feels slightly more intimate.

There isn't a direct opposite idiom, but 'Lab nadookhtan' (not sewing lips) or 'Zaban baz kardan' (opening the tongue) are related to speaking up.

Yes, in stories, novels, and informal letters, but not in formal reports.

Yes! It's a very sweet way to show your parents you are ready to help them.

Yes, in this idiom, we always use 'Lab' (singular), never 'Lab-ha' (plural).

Not necessarily. It implies the *request* is easy to make because the listener is so willing.

No, it's an idiom. It's informal but not 'street slang.'

Absolutely. It's very common in romantic lyrics.

You say 'Hatta lab tar nakard.'

Yes, it is understood and used throughout Iran and by Persian speakers in Afghanistan and Tajikistan.

Yes, it emphasizes that for the speaker, no favor is too big.

The imperative 'Lab tar kon' or the subjunctive 'Lab tar koni'.