My favorite sort of argument with a client:
Client: You forgot to bill me for this.
Me: No, I did bill you for it, and you’ve paid in full.
It’s nice because it shows how honest and thoughtful they are, AND for once, I get to be the person who remembered to do something.
Lisa Sorrell, cowboy boot maker 
I was wondering—do you ever forget to name the boots?
No, not really. Sometimes it takes me a while to think of a name I like though!