Being obstinate makes you look stupid.

I was minding my own business at work, while the Whistler was on the phone. Of course, he can't just have his phone conversation and get back to what he was doing, he has to tell me what he was on the phone about. He says to me..

"I never got my dental insurance card, so I called to ask for a new one."
Me: Um, yes you did, I gave them to you.
Whistler: (shows me his wallet) No I didn't!!! I got the two from the health insurance, but I never got dental ones.
Me: Yes.. you did. I handed out big packets of information on the dental insurance, and your cards were attached to the bottom of the first sheet.
Whistler: Oh, I bet I threw that away! (looks through his paperwork and finds the packet, but the bottom - where the cards were - has been cut off) No, here it is.. See, this is where the health insurance cards were, and I HAVE those, but not the dental ones!
Me: No. Your health insurance cards came in the mail. They're plastic. The dental ones were right there, they were paper, I remember when you got them. Another coworker got her packet, and I told her about the cards, and you went, "Oh! I didn't see there were cards down there!" and cut them out.
Whistler: Oh.. I should still have them then.. (looks through the rest of his wallet).. oh. Yeah, I do have them.