A man is going to the petshop one day, and he sees boxes with the signs: FROGS, LIZARDS and FROGS AND LIZARDS. However, the animals are in the wrong box. But the lizards will go "SHSHSHSHHSH" when the box is opened, and the frogs will go "R-I". You can only hear ONE box. Which one?

 

 

 

If you know the boxes are wrong, you need only to look at the LIZARDS AND FROGS box. Then you'll know the frogs were in the lizard's box, and the lizards were in the frog's box. You'll hear "SHSHSHSHSHSHSHSH R-I, R-I, R-I" when you open the L and F box.