Ineffective: You call that being?
Effective: You call that existing?
Ineffective: Will you ever grow up?
Effective: At exactly what time tomorrow will you grow up?
Ineffective: Could you change who you are now?
Effective: Could you please change who you are now?
Ineffective: You suck!
Effective: You are not proficient in many ways that permeate your being.
Effective: Live, damn you! Liiiiiive!! (also helps to pound on the chest of whomever you are criticising at the moment)
Ineffective: Dumb ass!
Effective: Stupid butt!
Ineffective: Could you do that again, but better?
Effective: Don't suck as much this time.
(Dear reader: Please submit your own for everyone's perusal in the comments section, and make sure they are good... sorry, I meant to say, make sure they are good, or you will be executed.)