One day, the old wise Socrates walks down the streets, when all of the sudden a man runs up to him "Socrates I have to tell you something about your friend who..."
"Hold up" Socrates interrupts him "About the story you're about to tell me, did you put it trough the three sieves?"
"Three sieves?" The man asks "What three sieves?"
"Let's try it" Socrates says.
"The first sieve is the one of truth, did you examine what you were about to tell me if it is true?" Socrates asks.
"Well no, I just overheard it" The man says.
"Ah, well then you have used the second sieve, the sieve of good?" Socrates asks "Is it something good what you're about to tell me?"
"Ehm no, on the contrary" the man answers.
"Hmmm" The wise man says "Let's use the third sieve then, is it necessary to tell me what you're so exited about?"
"No not necessary" the man says.
"Well" Socrates says with a smile "If the story you're about to tell me isn't true, good or necessary, just forget it and don't bother me with it.”