(I run a small nursery school. My kids are all four years old.)
Mother: I just can't understand why he's not potty trained yet.
Me: Well, sometimes it takes longer with boys. It might help to stop giving him diapers. A few accidents will teach him to be more aware.
Mother: Yes but it makes such a mess. (Turns to child) Time to go, baby.
Child: Mommy, I have to go potty.
Mother (to child): Well, we're leaving now. (Pause) Just go in your pull-up.