Hacker News Reader

That could be something the fridge can suggest, in email+notification+display on the outside [in flashing red]! You're on to something here!

Maybe the slapping hand (that warns you you've opened the fridge enough for the day) can be used to slap the back of the Ketchup bottle as well.

In order to maintain privacy, I'd suggest that the Heinz bottle compare a ketchup image to a hash of over-empty bottles.

The iHeinz can then send a notification to the manufacturer who then passes it to the Ketchup Police.