As a way to have more Fun in the classroom (after a difficult task)

I'd recommend using MadLibs.

Mad Libs is a phrasal template word game where one player prompts others for a list of words to substitute for blanks in a story, before reading the – often comical or nonsensical – story aloud. The game is frequently played as a party game or as a pastime (but can also be used in a class).

The game was invented in the United States, and more than 110 million copies of Mad Libs books have been sold since the series was first published in 1958.

How to play it? First of all, there should be a host. The host usually asks for parts of speech: nouns, verbs, adjectives etc. Example can be the following: Give me an adjective and you'll say any adjective you want. The host keeps asking you these kind of questions until the story ends. 

The funniest part is when The Host reads the whole story out loud with your suggested words. It is usually extremely hilarious. 

If you want to try this out, go to http://www.elibs.com