My favorite of them all!

If you put a spoonful of wine in a barrel full of sewage, you get sewage; if you put a spoonful of sewage into a barrel full of wine, you get…sewage.

If Murphy’s Law can go wrong, it will.

No matter which way you ride, it’s uphill and against the wind.

Gravitation is not responsible for people falling in love.

When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong.