So you're learning Romanian swearing?

"Mancati-as pula ta" is either a term of indearment or used to express surprise. The first is a filler word, similar in meaning to "you old dirty bartard" or "you sly motherfucker" for instance. The second is similar in meaning with "fucking shitballs!"

It is an awkward phrase to translate, as the gramatical structures used are different than what the English ones would be when the original meaning is preserved.

In the filler form, it's similar to "... si atunci, pula mea, am mers cu ala..." -- it does not transmit information so it's deceiving to consider it has a gramatical form that needs translation.

See the classic Bujor la pacanele, and also the ultimate clip to explain this phenomenon.