Being three seems like hard work. Everything is epic. Everything is remembered. Everything is mimicked.
All kids have their days when everything is tough, even Parker, which I know is hard to believe since I talk about him like he is a saint. He yells during church to hear the echo, he lays on the floor at the post office, and he cries when I turn off the TV.
Parker is rarely deliberately naughty. Every once in a while he does something that he knows is against house rules because he is mad at us or wants attention. But most of the time, he is just learning.
As a teacher I have heard parents make excuses for their children: he is tired, he saw his cousin do that, he is shy. I am not saying that I have never said those things, truth is, I usually do know exactly why Parker is behaving in a certain way. But I don't think that is a free pass for misbehaving.
Parker gets time-outs often. He knows the drill. All I have to say is "that's a time-out" and he usually goes right to his chair. He knows that he has 3 minutes and can even set the timer himself. On his way I calmly state his offense "you are in time out for hugging your sister too hard" or "it is not okay to poke a friend" or "you may NOT go outside by yourself". Then I walk away. When the timer beeps, he turns it off and comes to me. We hug, I repeat his offense again, he tells me he is sorry, and then we continue on with our day. Sometimes Parker makes an excuse of his own like "I got frustrated, that made me sad, or I am hungry". I take the opportunity to validate his feelings and teach, "It is okay to feel frustrated, but you cannot throw my phone. What you can do is ask for help. I would love to sit with you and help."
We all have moments as parents, where we think "I can't believe I just did that, or said that, or let my kid eat that". I am not perfect, but I am proud of how we choose to discipline our children. We have been doing this since he was old enough to understand cause and effect (maybe 1 or 1.5 years old). It eliminates unwanted behavior, teaches what is appropriate, and is consistent. It works for us.