Mrs Muhulu and the Accidental Ineffective Witticism

The doorbell wasn't working and the door itself was covered in sound-deadening felt.

 

"KNOCK KNOCK!" Mrs Muhulu shouted through the letterbox.

 

"Who's there?" came the voice from the other end.

 

"MRS-!" cried Mrs Muhulu, before she was interrupted by a coughing fit, due to the shouting.

 

"Mrs who?" came the voice from the other end.

 

"MRS MUHULU!" called Mrs Muhulu when she got her voice back.

 

"That's not much of a joke," came the voice from the other end.