[Arvon]

father brought his son into the doctor because the boy had a matchbox car
shoved up his nose. All the while the doctor was trying to remove the car,
the father kept saying "I don't know how he did it!" Finally the doctor
removed the car, and the father and son left.
A few hours later, the father came back with the matchbox shoved up HIS
nose. He told the doctor, "I know how he did it!"