- If you are looking for other laws, see our longer Eponymous laws
- Murphy's law:
- If it can go wrong, it will go wrong.
- If it can go wrong, it will go wrong at the worst possible time.
- 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 law will never be in effect when you want something to go wrong (though recursively, this is Murphy's law in action). For example, though washing your car usually seems to bring rain, washing a car in order to bring rain will assure clear, hot, dry weather -- unless that was your intent. (Also known as the Law of Murphological Inapplicability.)
The original name for the concept of anything that could go wrong will go wrong was Sod's law This name is less popular now than Murphy's law now. The name Murphy's law allegedly originated from Capt. Edward A. Murphy who was an engineer in the US army in 1949 who declared of a technician "If there is any way to do it wrong, he'll find it". Murphy's law gained popularity when an aerospace engineer from the same army base gave a press conference mentioning that the success of his project was as a result of following Murphy's law, and the name caught on 
 Examples of Murphy's law
- When you drop toast it will land butter side down (unless it is strapped butter-side up to the back of a cat, in which case undefined behaviour will be exhibited).
- When waiting for a bus, every other bus will show and just when you get sick and tired of it all and light a cigarette your bus will arrive.
- When drinking quietly and secretivity while your girlfriend is out with friends you'll get to the point wherein you only have one beer left but you don't want to open it because you don't want to appear to be drinking when she arrives. After an hour and she hasn't arrived you open it, thinking all is calm, and then she walks in the door and accuses you of being drunk.
- A valuable dropped item will always fall into an inaccessible place (a diamond ring down the drain, for example) - or into the garbage disposal while it is running.
- ↑ Retrieved from here although there is no real evidence that any of this is true.
- ↑ Only applicable in areas where buses are smoke-free.