Monkeys.

Did you know that monkeys in Bali snatch stuff from tourists, and use it as bait to demand food in return?

Scientists actually filmed them doing so: they noticed is that the higher the value of the object stolen (say, a smartphone), the more food they want in return.

Shortly after posing for a picture with me, this VERY innocent-looking guy stole a smartphone from a (desperate) tourist who was taking a picture of a tree.

And you can see one here stealing flip-flops. ↓