"Shove it up your colon ..."

The story:

As I was receiving nitrous oxide in preparation for the extraction of my wisdom teeth, I was singing "my" version. My dentist, who in his twenties, had been a road manager with Glenn Miller's orchestra, and corrected me. Since I was drugged up in a chair at the mercy of someone who had every pain-inducing instrument ever created at his disposal, I was in no position to argue.