Why so many keys are so rusty????? Please answer.

Why Why Why

 
Woman asks:

If I sleep with 3 men, everyone calls me a slut. But when a man sleeps with 10 girls, everyone calls him a real man. How come? Man replies:

It's very simple.
Confucius say 'When one lock can be opened by 3 different keys, it's a bad lock.
But when one key can open 10 different locks, we call it a master key!'.