We’ve all been there; that horrible moment when you realize that you’ve forgotten your keys and locked yourself out of the house. It’s hard these days to leave a key in a “secret” place like under the doormat or in the mailbox, as these hiding spots are too common to remain secret for long. But this brilliant solution to the problem will ensure that you never get locked out again, and that potential burglars don’t get in either. Check out Household Hacker’s great idea: