My daughter's behavior...well frankly...was atrocious at 3...GOOD LORD I mean seriously! It has lessened now that she is closer to 5 however her negotiations are more sophisticated and she can be quite manipulative. I mean when she was 3, we were in a veterinary's waiting room and had some McDonalds. So I told her to throw it away in the garbage can across the room. She went over there and stopped by the man sitting next to the garbage can and asked him to throw it away...guess what he did? The 1st 2 guesses don't count...needless to say yes, my daughter can get adults to do what she wants them to do quite often which enables and can exacerbate her behavior.
Sometimes my daughter acts like 30, and other times she acts like she's 2. When she's acting like she's 2, I have to stand my ground. I will ask her if throwing her little temper tantrum will get her what she wants...she typically stops and says "no"...again she knows the rule...she just keeps hoping that I'll turn stupid I guess. :o)