You need to get creative. For example, I saw the video below in the comments section of a post on Pandagon, referenced in Making Light Particles as "Pandagon FAQ, draft version". It's a response to the question "It’s so cool that Amanda’s got a book deal! But why is it taking so long for her to finish?"
Click Here for more great videos and pictures!
Here are some suggestions - feel free to use them.
"I got my protagonist lost in some underground caves and can't figure out how to get him out of there until I finish reading these 42 articles I Googled on spelunking."
"My horoscope told me this was a bad week for using my imagination."
"I have to make sure I'm keeping up with this thread on Absolute Write about Pirates of the Caribbean 3."
"I've decided that only celebrities get published, so I'm taking acting (singing, dancing) lessons instead of writing."
Feel free to suggest more in the comments.
Edit: J M McDermott suggested these in the comments:
I'd finish my WiP, but I'm WAY too drunk, all the time.
Also, Helena Bonham Carter keeps calling and calling me. I mean, seriously, how many times do you have to explain that "No" means "No".
My coffee machine broke. I've tried replacing it three times, but so far all I've managed to pick up are a waffle iron, a llama's bridle, and two illegal immigrants named juan valdez who keep offering me matte lattes - NOT COFFEE! shopping for a coffee maker seems to also require coffee.
I'd finish my WiP but people keep asking me what's taking so long. I spend more time answering that question than I do actually writing.
Also, I blame your (whoever happens to be asking) fascinating blog.
Other things around the blogosphere I've seen recently and made me think, on the topic of writing:
"So You Think You Can Write, or Tales from the Slush Pile"
"Five Years Later...(The Origins of International Slushpile Bonfire Day)"
"Five Top Reasons You Should Stop Calling Yourself a Writer, Right Now"
That whole writing thing is hard work. I have enormous respect for anyone who can stick with it. Anyone who says to themself, "I could do that" or "what's so hard about being a writer" should spend some time following links on agent blogs, writer's blogs and reading the forums at AW. If the amount of work needed to become a good writer doesn't faze you, you may have a decent chance. I recommend you start your education at Learn Writing with Uncle Jim.
Whatever you do, no matter how frustrated you get, don't send your book to Publish America. Please.
There's a new AW blog-chain going on - I hope you'll visit them:
Virginia Lee: I Ain't Dead Yet!
hunt & peck
Life, Writing, and Other Things
A View From the Waterfront
The Road Less Traveled