Murphy and other laws
The classic Murphy's Law and other related ones.

• Whenever things sound easy, it turns out there's one part you didn't hear.
• Achenson's Rule of the Bureaucracy: A memorandum is written not to inform the reader but to protect the writer.
• If there is a possibility of several things going wrong, the one that will cause the most damage will be the one to go wrong.
• If there is a worse time for something to go wrong, it will happen then.
• Success always occurs in private, and failure in full view.
• Airplane Law: When the plane you are on is late, the plan you want to transfer to is on time.
• The bag that breaks is the one with the eggs.
• The more an item costs, the farther you have to send it for repairs.
• You never want the one you can afford.
• Never ask the barber if you need a haircut or a salesman if his is a good price.
• If it says "one size fits all" it doesn't fit anyone.
• The least experienced fisherman always catches the biggest fish.
• The one item you want is never the one on sale.
• Enough Research will tend to support any theory.
• The legibility of a copy is inversely proportional to its importance.
• Acton's Law: Anybody can win -- unless there happens to be a second entry.