Here’s a starting point for some wasted time: http://en.wikiquote.org/wiki/Murphy .

Although some are funny, and most are true.

These might be appropriate for any weekend projects:

• Any tool dropped in a workshop will roll to the least accessable corner. Any object dropped on the way to the least accessable corner will land on your toe.
• Anything you try to fix will take longer and cost you more than you thought.

My addition to those: “Any project will require at least three trips to the hardware store.” I’ve been bit by that one several times.

As seen by my Home Depot bills.