In Ramayana, When Rama wanted to build a bridge across the ocean to Lanka, monkeys started to carry big boulders and stones. A squirrel came in the way carrying a pebble. Monkey asked the squirrel to get out of the way and asked what the squirrel was doing there..
The Squirrel said he/she was helping build a bridge for Rama. Then the monkey laughed at the squirrel and made fun of the squirrel and his/her action. The monkey had the opinion that squirrel is too small and cannot carry more than small pebbles. And so the monkey was amused at the foolishness of squirrel and his/her thinking big action like helping Rama.