Andrew Meyer has created the Project Management Excuse List.
Have you ever sat in a status meeting and thought, "I've heard that excuse before, and that one and that one too..."?
He's created a nice list of excuses for why your project is late this time. And, as with similar lists, he suggests using the excuse number as a shortcut for your explanation. (Imagine going to a restaurant and ordering the #11 for starters and #34 for the entree.) Should save all sorts of time in meetings.
Several people have added more in the comments. I added number 23:
23. I've spent the last [time period] on a critical customer issue.
[found via a repost of the question into LinkedIn Answers.]