It was a dark winter night, and among the usual queue of studded leather, chained piercings and rubber appendages, the S&M club's bouncer was surprised to see a man in an expensive suit and tie standing patiently, a calculator in one hand.
"Sir, are you lost?" asked the doorman.
"Oh, I'm the statistician." came the reply.
"Then, what are you here for?"
With an unsettling grin, the statistician pulls out a knife.
"Oh, just standard deviation."