An agreeably unhinged slapstick jamboree. It pretends to star Robin Williams, gently updating Fred MacMurray?s convolutions in The Absent-Minded Professor. But its true star?its only star, really?is Flubber, the shape-shifting candy green blob of ?flying rubber? that Williams? Professor Brainard invents. The Flubber bounces around rooms and performs a full-tilt Mambo King/Astaire-and-Rogers number. It zooms through a villain?s intestines and comes shooting out of his rear end. (Top that, Jim Carrey.) The special effects are the whole show, but there are far less entertaining things to see in a movie than Robin Williams being outacted by rocketing Jell-O.