My four year old girl has picked up some bad habits also. With her, it's from hanging out with a neighbor girl who whines all the time and pouts like a baby. It drives me nuts. For us, I decided to sit down with her and write out a "discipline chart". Since we did it together, it gave her a sense of control over what would happen, so she does better when I have to enforce the punishments. We have five actions on it and every single time, no exceptions, that she does something from the list, we go to it and read what her consequence is. They range from giving me money out of her allowance piggy bank, because she HATES that one, to spankings and time outs. It's really worked for us, plus I notice a huge difference in my own patience because I don't have to get all worked up anymore, I just simply walk to the list and the punishment is already decided. It is also a magnificent way to teach a child about consequences.