The Cockroach

A man is sitting at home one evening when the doorbell rings.
When he answers the door, a 6 foot tall cockroach is standing there.
The cockroach immediately punches him between the eyes and scampers off.

The next evening, the man is sitting at home when the doorbell rings.
When he answers the door, the cockroach is there again.
This time, it punches him, kicks him and karate chops him before
running away...

The third evening, the man is sitting at home when the doorbell rings.
When he answers the door, the cockroach is there yet again.
It leaps at him and stabs him several times before making off.
The gravely injured man manages to crawl to the telephone and summon
an ambulance.

He is rushed to intensive care and they save his life.
The next morning, the doctor is doing his rounds. He asks our hero
what happened.

The man explains about the 6 foot cockroach's attacks, culminating in
the near fatal stabbing.

The doctor thinks for a moment and says, "Yes, there is a nasty bug
going around."