Swallowed a mouse

"Doctor, doctor!" said the panic-stricken woman, "my husband was asleep with his mouth open, and he's swallowed a mouse! What shall I do?"
"Quite simple," said the doctor calmly. "You just tie a lump of cheese to a piece of string and lower it into your husband's mouth. As soon as the mouse takes a bite ¨C haul it out."
"Oh, I see. Thank you, doctor. I'll go around to the fishmonger straight away and get a cod's head."
"What do you want a cod's head for?"
"Oh- I forgot to tell you. I've got to get the cat out first!"