While chasing the white rabbit, you become distracted by a large and droopy caterpillar.  He points to a mushroom, belches and says "One side will make you bigger.  The other side will make you smaller."  He does not tell you which side is which.  He then slides off the leaf with his sticky feet in the air.  Slowly, he disappears as he inches further into the grass.  What do you want to do? 

Eat from the front of the mushroom. or Eat from the back of the mushroom.

 
The caterpillar serves as a common type of character in interactive fiction.  He appears out of the blue to provide information that Alice would otherwise have no way of knowing.