We have a 4 and 14 with some 23 on the side

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.]