This is blatantly stolen from a show I loved (when it was on) Drew Carey's Whose Line Is It Anyway? I forget what the game was called, (it may have been 'Sentences') but it was one that almost always had me in stitches. 

This works best with a group. If you don't have a group, get one, they're good for you. In the meantime, see the Solo Alternatives below.

First: everyone has to write several completely disconnected sentences down on separate pieces of paper. If you want to make it a challenge (usually with hilarious results) make them absurd. As an example, the episode of Whose Line from which I stole this idea had the following sentences (taken from the audience before the show):

• I can't hear you, I spilled coffee on my pants this morning.
• Are you always this purple?
• Did you know I'm a woman?
• I see Paris, I see France, I see someone's underpants!

The last ended up being used as the Famous War Cry of Braveheart. Yeah. Anyway. Get some sentences. Everyone should write about 5 for a short game, 10 for a longer one.

Solo Alternative: Grab six random books, preferably at least one of them non-fiction, open them up randomly and take random sentences from them. And I mean 'random', not 'random until I find something interesting or usable'. Do this until you have twenty sentences. For preference, do this the day before, so you forget what they are.

Put the sentences in a hat, bin, or receptical of your choice. Shake 'em about, and everyone draws out 5 or 10 (short or long) without looking at the sentences. Do not look. Not even to check if you have your own - it doesn't matter if you got your own (if you were trying to be difficult and wound up with your own, that's probably karma for you). Everyone sits down with their sentences, still not looking at them.

Solo Alternative: Same thing - stick 'em in a hat, draw out 5 for a quick game, 10 for a longer one.

Look at the first sentence. This must be your first sentence. Write it down. Continue the story - write more sentences after it that make it make sense.

Every so often someone shouts "Line!". Then you take the next random sentence from your pile, look at it, and find a way to work it in. You have one grace sentence with which to play - that is, you can write one more sentence of your own before you have to write the random sentence. You may wish to organise who shouts 'Line!'. Personally, I prefer to leave it available to anyone - people tend to shout it when they're running out of ideas, and if anyone can shout it you'll never know when it's coming.

Solo Alternative: Have some kind of randomised timer (there's probably computer software that can do it) or a regular timer that sits behind you (so you can't see it and prepare). Set it for a minute or two, and whenever it goes of you have to include the next random sentence.

You can also try this with everyone having the same sentence (even in the same order, perhaps). I find that way has less varied results, but it's a good ice-breaker to have everyone dealing with the same sentences and the same "there's no way this could make sense!" desperation.