People are funny, that's why

We were hanging out on the couch again, my son and I, after a difficult day (difficult as in lots of yelling between unhappy siblings resulting in yelling from me). I ask my son why he rolls his eyes when he knows I don't like it and that his tone of voice is disrespectful when I talk to him during the day, but, during the evening, he is much kinder and more respectful.

He says, "Well, people act differently and sometimes they don't know why."

Hmm, no kidding.