Those are my principles, and if you don't like them... well, I have others.
I could dance with you until the cows come home. On second thought I'd rather dance with the cows until you come home.
Heifer cow is better than none, but this is no time for puns
I never forget a face, but in your case I'll be glad to make an exception.
I've got the brain of a four year old. I'll bet he was glad to be rid of it.
He thinks I look alike!