Probably as you're waiting for your conditioner to absorb or right when your body does that weird jerky thing before you fall asleep, a stroke of shower/nighttime genius darts across your cerebral cortex. "I better write this down," you say as you immediately think of something else, perhaps that raspberries make great hairpieces for Lego action figures. (But you remember the idea later, which is enough evidence of its promise.)
2. False hope
If this were a meme, the caption would be "When you're really excited for something that could be big but might not be, and you don't want to jinx it by pushing too hard too early." Here is the pic.
[While making flapping motions with hands]: What if someone already thought of this? OMG WHAT IF SOMEONE THOUGHT OF THIS BUT THREW IT INTO THEIR REJECT PILE? [Two weeks later, after having made a draft, put it away, and come back to it]: Why, yes, I am garbage. (See next stage.)