The Foam That Broke The Camel's Back

A bad, airy, non-defined business idea that you think of to distract yourself from doing work you are meant to be doing even when you already have 5 businesses on the go and 100 ideas in the works.

"Hey man, what are you up to?"
"Doing my tax return. Hey, do you think I could make a product where you completely fill the inside of a car with foam and it cleans while it dissolves?"
"Dude, that'd be the foam that broke the camel's back"