Like when you tell your son to leave his little sister alone and literally right after you say it he kicks her in the face.
Those are the moments I stand there dumbfounded for a minute wondering if the time my son fell of the bead headfirst as a baby somehow messed with his hearing. I will never understand how a child can sit and listen to you say something and the next millisecond they are doing precisely what you told them not to do.
And you know what the worst part is? It just gets worse as they get older. I am counting down to when all three of my kids are adults and out of my hair : )