Murphy's Law
When people hear of Murphy's Law they usually think of the original law:
Everything that can go against you will go against you, or:
The light at the end of the tunnel is just the headlight of an oncoming train...

But this Murphy's Law is nicer to humanity and makes people far more positive.
And it goes like this:

Whenever cold outside, go to the pub and have at least three pints of Guinness.
Whenever hot outside, go to the pub and have at least three pints of Guinness!

Live by this and what can go wrong???? And keep in mind: It never rains in the pub....

They're flying away with my Guinness!!