When discussing the age of the universe. I sometimes run into the statement "How long is a day". This is an attempt by theists/deists to reconcile the actual age of the universe (13+ billion years) with the 6 days (or 6000 years) in some scriptures.
My first reaction is "You're nuts", but I don't think that would be persuasive. I sometimes try "calling a dog a cat does not change all dogs to cats". But, I am looking for something better. Any suggestions ?