Question Friday - How Do You?

Here we are again - it's Friday and that means it's time for our new meme here at WordWranglers. It's Question Friday! I took the question this because ... well, it happened to me. So, without further ado, our question:

You get a brilliant idea - plot bunny, piece of dialogue, insight into your character, whatever - at a totally inappropriate time - while driving, in the shower, in the dentist's chair, whatever - what do you do?

Liz said, "If I can, I put a note on my phone or write myself one...