I can think of many reasons for having a secret hiding stash. It's an extra deterrent for burglars. You've just moved in with someone and haven't yet told her about your immense cookie jar collection. Or, more simply, you're paranoid. You know what they say: "One man's blanket storage is another man's secret junk food stash."
Here's a round up of projects to help you hide your valuables and embarrassing behaviors:
And, if all else fails, just go buy this and stick it in your fridge:
10. Iceberg Lettuce Safe
Do you have a secret hiding spot? Do tell...
(Images: as linked above)