I also hate the custom of saying "Bless you" when someone sneezes.
This custom started centuries ago, when Europeans believed that illness was caused by 'evil spirits' infesting your body.
Bring on the leeches and bloodletting!
We don't live in the dark ages anymore. Can we drop this stupid saying now?
"From the mouths of babes...", normally uttered when the little darling cusses or repeats something mommy or daddy said about someone, in front of the person in question.
or along the same lines... "Where did they pick up something like that?" ... Yeah where, considering it's your kid, who spends 100% of his/her time with you?