The mother scolding the hotel concierge?
In the scene when the McCallister family arrives at the Plaza Hotel, the mother looks really mad.
When she asks the concierge (Tim Curry), "Why did you let (Kevin) leave (the hotel after finding out about the credit card)?", she sounds a bit - mean? I don' t know, I watched the movie for the first time in years and just noticed this. I though: "Oooh - she sounds nasty!"
She didn't directly tell off Curry, although she then gave him a slap which reduced him to tears. XD