Given some of the interest about this rule, I thought I'd write it up in more detail since I'm not downstairs spinning my brains out and legs off.
Picture yourself minding your own business on a river bank. The river is a metaphor for the world. One day an elephant floats by in a canoe, or in a barge, or whatever. You've heard of elephants, but never seen one. You stop what you're doing, and watch it float by.
Now, it is futile to speculate on how the elephant got there, where it's coming from, where it's going, what will happen there, if the elephant is enjoying the process, who is worried about the elephant, or an infinity of other questions. There are an infinity of answers to each of these questions, and to explore them is to follow a road that George Cantor has already explored. You have better things to do with your time.
It is even more futile to swim out and try to ask the elephant questions or investigate the situation. You will only be dragged further from home every minute. There will be no explanation written out neatly for you and elphants are known for not having much to say. You will only discover more questions. Plus, you run the risk of the elphant thinking that you are interfering with it's plans or that you are a toy to play with. You have better things to do with your time.
Worst of all is to bring it back home with you, even if it seems amiable. It will eat you out of house and home, and since it's found an obliging human, it will never leave. If you try to make it leave, it will resent you, and keeping coming back. Elephants are known for having good memories and being stubborn. Whatever else you had going on in your life now includes taking care of an elephant until it chooses to leave. You do not want this to happen.
The odds of getting rich from the novelty of owning an elephant by charging admission to ride it, or by taking a commission on the paintings it creates is very, very small. Don't forget that many municipalities have rules against having pets that large, and the few that don't charge large licensing fees.
So what do you do? You just watch it go by, then go back to what you were doing. You might want to look at it carefully so you can describe it to your friends and family. But that's all. It floated into your life, and if you let it, it will float out.
Now, this came up in the context of married men, and their relationships with their wives. Everybody that's been married knows what I'm talking about. Guys, virtually everything your wife says and does is a floating elephant. The correct response is to smile, say "Yes, dear", and go about your business. At least, that's as correct as a married man can ever get.
But I've discovered it works everywhere. As soon as you start identifying situations, or people, or ideas as floating elephants, you wil find your life is enormously simplified. Plus, in some circumstances, it's outright hilarious in ways that you can never explain to anyone else.
There is one further possibility related to floating elphants that you need to be aware of. Very rarely the elephant will come aground beside you, either by accident or on purpose. I'm sorry to say that once this happens the elphant is not likely to float away again, and you probably have to DO something about it. The rule in this case is known as the Andy Kelp rule. "Every day is another opportunity to triumph over the unexpected." Good luck, and let me know how it turns out.