From Steve Martin:
Writer’s block is a fancy term made up by whiners so they can have an excuse to drink alcohol. Sure, a writer can get stuck for a while, but when that happens to a real author — say, a Socrates or a Rodman — he goes out and gets an “as told to.” The alternative is to hire yourself out as an “as heard from,” thus taking all the credit. The other trick I use when I have a momentary stoppage is virtually foolproof, and I’m happy to pass it along. Go to an already published novel and find a sentence that you absolutely adore. Copy it down in your manuscript. Usually, that sentence will lead you to another sentence, and pretty soon your own ideas will start to flow. If they don’t, copy down the next sentence in the novel. You can safely use up to three sentences of someone else’s work — unless you’re friends, then two. The odds of being found out are very slim, and even if you are there’s usually no jail time.