"Doctor, are you sure I'm suffering from pneumonia? I've heared once about a doctor treating someone with pneumonia and finally he died of typhus."
"Don't worry, it won't happen to me. If I treat someone with pneumonia he will die of pneumonia." Full text

A guy walks into work, and both of his ears are all bandaged up. The boss says, "What happened to your ears?"
He says, "Yesterday I was ironing a shirt when the phone rang and shhh! I accidentally answered the iron."
The boss says, "Well, that explains one ear, but what happened to your other ear?"
He says, "Well, jeez, I had to call the doctor!" Full text