There's an obscure form of the pun called a "degenerative pun".  Start 
with a simple statement, then go from there:

Why was the "Story of O" banned in the US ?
Too much sex and violence

        (and, we're off...)

Why was "Ivanhoe" banned in the US ?
  Too much Saxon violence


Why did the NFL ban macho razor blade commercials ?
  Too much Schicks and virulence


Why did the woman hate VapoRub & not talking for laryngitis?
  Too much Vicks and silence


Why did the woman quit dying her curtains for 27 windows ?
  Too much soaks and valances


Why was the chip dipping, potato chip eating optician fired ?
  Too much snacks and vile lenses


Why did the Lord of the Manor punish the surly Serfs ?
  Too much sulks and villeins


Why did the orchestra leader quit ?
  Too much sax and violins


--Courtesy of Jim Moore Jr.