31st May (Tuesday) is the Final Day for the 2016 Wit & Humour Exhibit    presented at Main Branch of San Francisco Public Library. This event is    sponsored by the Books Arts & Special Collection Center.   The Exhibit is on display from April 1 and this year`s the special feature is    Animal House : Anthropomorphic Selections of political humor, assorted    cartoons and international collections.   Photo courtesy if SFFunCheap