The plumber opens his bag

A doctor finds in the middle of the night that his basement is under water.

 Immediately he calls a plumber. 

However, he refuses to come at this late hour.

 As a result, the doctor becomes indignant and declares that he also has to come in the middle of the night if it is an emergency.

 A quarter of an hour later, the plumber is there. 

Together with the doctor,

he descends the basement stairs,

half of which is already under water. 

The plumber opens his bag, takes out two sealing rings, throws them into the water and says,

” If it’s not better tomorrow, call again. “