What do you do when one of your friends laughs when you say you're confused?

As Katie and I were talking tonight, I’m trying to tell her about my week. I’m all, “Oh! I realized something this week.” Then my mind goes blank. She’s over there laughing her head off.
Which of course makes me laugh. It’s frustrating because I’m trying to remember this great thought I had that I wasn’t smart enough to write down and she’s laughing!
We have a moment of silliness then continue talking.
I know she wasn’t laughing at me; she was just laughing because it’s funny to hear since I always get there in the end.
Do any of ya'll have friends like this or are Katie and I alone in this?