Things you can say to a good buddy: 1. You're such a troublemaker. 2. Don't be such a pain in the ass. 3. You like yanking my chain, don't you? 4. Enough monkey business. 5. Happy now?

You would NOT use "a" trouble. The "a" is an indefinite article that isn't needed and makes the sentence a bit awkward to a native. However, you can say: "Are you gonna be a "pain" for me?" In this sentence, "pain" is a slang term (or generic word) that can be used for someone who's "bothersome". IF you really wanted to ask the second question, it would be better to say: "Are you gonna be a pain in MY ass?" By using "the" (which is a definite article) you are saying a specific ass, however, you aren't saying which ass. By saying "for me", you are literally saying "are you going to be a pain in some unknown specific ass for me to deal/put-up with?" By substituting "my" for "the" and dropping "for me", you are now saying: "are you going to be a pain in my ass... (one that will very much bother me)?"

Either would work, but I'd use the second one unless your dealing with a boss, etc.