When you want to lecture someone about their behaviour today, they already know, deal with it another way.
You will feel the need to give someone a bit of a lecture today, most likely about their recent behaviour. They wont listen and they already know how you feel about this, so if you go ahead and give them a piece of your mind all you are doing is wasting your energy. You might think it will make you feel better, but there are other ways to deal with this.