Which is the real one?

from here and here (image source)

Presumably one of those doors is an actual entrance and the rest are just decoys, but you'll have to figure out which is which before you can try breaking in.

Dueling Decoys

found on Funny Junk

Imagine the kind of statement this makes. Not only did the allied forces go to the trouble of producing a fake wooden bomb, they used real fuel to fly over and deliver it to it's target. They were so well informed about what the enemy was up to and so well prepared that they could afford to troll the enemy in such a demoralizing way. I bet this made the Germans think twice about using this tactic again.

Never gonna give up my privacy

found on Imgur

This is a pretty good example of a decoy. Imagine going that deep and finding nothing but Rick Astley - would you keep looking? I mean, sure, someone could do a search instead of just clicking on folders, but for those not smart enough to do that (like maybe your little brother/sister)  this may actually deter them from finding anything really private.