Murphy's law
If anything can go wrong, it will.

Corollaries
1. Nothing is as easy as it looks.
2. Everything takes longer than you think.
3. Anything that can go wrong will go wrong.
4. 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. Corollary: If there is a worse time for something to go wrong, it will happen then.
5. If anything simply cannot go wrong, it will anyway.
6. 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.
7. Left to themselves, things tend to go from bad to worse.
8. If everything seems to be going well, you have obviously overlooked something.
9. Nature always sides with the hidden flaw.
10. Mother nature is a bitch.
11. It is impossible to make anything foolproof because fools are so ingenious.
12. Whenever you set out to do something, something else must be done first.
13. Every solution breeds new problems.

Murphy's Law of Research
Enough research will tend to support your theory.

Murphy's Law of Copiers
The legibility of a copy is inversely proportional to its importance.

Murphy's Law of the Open Road:
When there is a very long road upon which there is a one-way bridge placed at random, and there are only two cars on that road, it follows that: (1) the two cars are going in opposite directions, and (2) they will always meet at the bridge.

Murphy's Law of Thermodynamics
Things get worse under pressure.

The Murphy Philosophy
Smile . . . tomorrow will be worse.

Quantization Revision of Murphy's Laws
Everything goes wrong all at once.

Murphy's Constant
Matter will be damaged in direct proportion to its value

Anything that can go wrong will go wrong.

It is impossible to make anything foolproof because fools are so ingenious.

Left to themselves, things tend to go from bad to worse.

Rule of Accuracy: When working toward the solution of a problem, it always helps if you know the answer.

Corollary: Provided, of course, that you know there is a problem.

Nothing is as easy as it looks.

Everything takes longer than you think.

If anything simply cannot go wrong, it will anyway.

Whenever you set out to do something, something else must be done first.

Every solution breeds new problems.

The legibility of a copy is inversely proportional to its importance.

Matter will be damaged in direct proportion to its value

You cannot successfully determine beforehand which side of the bread to butter.

The chance of the buttered side of the bread falling face down is directly proportional to the cost of the carpet.

The chance of the bread falling with the buttered side down is directly proportional to the cost of the carpet.

You will always find something in the last place you look.

No matter how long or how hard you shop for an item, after you've bought it, it will be on sale somewhere cheaper.

The other line always moves faster.

In order to get a loan, you must first prove you don't need it.