Murphy's Second Law: Everything takes longer than you think.
Murphy's Third Law: Whatever can go wrong, will go wrong.
Murphy's Fourth Law: 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.
Murphy's Fifth Law: If anything just cannot go wrong, it will anyway.
Murphy's Sixth Law: If you perceive that there are four possible ways in which a procedure can go wrong and circumvent these, then a fifth way, unprepared for, will promptly develop.
Murphy's Seventh Law: Left to themselves, things tend to go from bad to worse. (Farnsdick's corollary: After things have gone from bad to worse, the cycle will repeat itself).
Murphy's Eight Law: If everything seems to be going well, you have obviously overlooked something.
Murphy's Ninth Law: Nature always sides with the hidden flaw.
Murphy's Tenth Law: Mother Nature is a b----.
Murphy's Eleventh Law: It is impossible to make anything foolproof, because fools are so ingenious.