When is it a good time to Lie?

A friend of my wifes who is a married mom of 2 her oldest son is in middle school, she went to a special program at school to help out. Her son came home and said a couple of boys said she was a MILF and he didnt know what they meant. She didnt either and asked my wife and I if we knew my wife wasnt sure and I said I had no idea. I lied!