The full sentence

Well, for grammerical Well, for grammatical perfection, the full sentence should be:

I have been there, I have done that.

Normally, this relates to a conversation about a piece of common experience – implied in words “there” and “that”, in a tone of suggesting consent to the other party in the dialogue. The the “complete” sentence may look like this:

Yeah, I hear you – I have been there, I have done that.

But for short, it comes out as:

Been there, done that.

閑著沒事，樂一樂，俺沒有那麽學究。多哥的好心看得見，大局不虧，小處的那種窮講究不要也可。