With my son we have been trying to teach him that his baby sister is fragile so he doesn't mash her into pieces. He is actually quite good with her but being a 4 yr old boy he needs to be reminded from time to time to be careful. Well the other day he was talking about his baby sister and said the following:
The Boy: Girls are fragile.
Me: Are boys fragile?
The Boy: No, boys aren't fragile. Boys are tough.
Me: So you are a tough boy?
The Boy: Boys are tough because they don't cry about boo-boos.
The rest was me laughing about the tough boys and their boo-boos.