Biggest Cavity

- Open wider. - requested the dentist, as he began his examination of the patient.

- Good God! - he said startled.

- You've got the biggest cavity I've ever seen - the biggest cavity I've ever seen.

- OK Doc! - replied the patient.

- I'm scared enough without you saying something like that twice.

- I didn't! - said the dentist.

- That was the echo.