When you pour a bowl of cereal, and all that comes out is the yucky cereal sawdust. Seriously.
And my family has the incurable disease where we can't finish boxes of cereal, and we definitely can't throw away a box that isn't totally empty, so instead, we put the 99% empty box back on the shelf. The worst thing about this disease is that it's genetic. My whole family has it. Which means that I've had a gazillion experiences where I go to eat cereal only to realize my first choice isn't actually available. This happens until someone (usually mom) gets fed up and throws a whole bunch of boxes away.
But that only makes us look like we have no cereal, so dad buys more and it's not very long until we're pouring cereal sawdust into our bowls again.
And seriously, Cheerio sawdust tastes the worst.