two elephants go tae a shower .one elephant say,"pass the soap" the other elephant says ,"no soap radio " No soap radio is a traditional punch line for a prank joke.
punch line:is the final part of a joke or comedy sketch prank:is a trick to purposely make someone make foolish or victimized, usually for humor
Well the punchline no soap radio was used as a test in the 1940's and still used today to see if people will agree with the other person telling the joke even if its not funny to see if people will agree and pass judgment.