@manored,
A local lothario walks into the doctor's office and demands to speak to the doctor as it is an emergency.
The doctor comes out and asks what's the matter.
The lothario says, "I can't get it up... and I've tried everything doc!"
"Ok", says the Doctor, "what have you done so far?"
"I've tried beating it"
"ok", sais the Doctor
"I've tried stroking it"
"ok"
"I've tried watching adult films"
"ok"
"Doing these has always gotten it to go up! Why isn't it doing it now?"
The doctor sighs and walks back to his desk. "Don't you know the problem of induction? Just because it happened in the past, doesn't mean it'll happen in the future!"