To me it sounds like a common phrase/idiom. However, Google disagrees.
Climbing up the tree again? Oh, you lil stubborn.
No, it's not.
My guess is that it's a fragment from something like, "the stubborn little hellion that you are....". Or it's a fragment of a common saying such as, "why you little stubborn bastard/child/idiot/fiend/brat/etc.".
It's absolutely not a common idiom. In fact, as presented, it's not even a complete sentence. That's why I say it's most likely a sentence fragment and furthermore if there is more to the sentence then it's still probably an idea fragment created from one of those phrases.