One of the universe's depressing cruelties (besides genocide, rape, hunger, et al.) is that one can neither nuzzle with nor scratch the belly of a giant bear. Because said giant bear will probably kill you. Take, for example, Ulu, a 30 year-old female polar bear at the SF Zoo. Pictured here, Ulu enjoys fresh snow courtesy of the San Francisco Ice Company on Wednesday at the San Francisco Zoo. But if you played with her, as inviting as she appears, she could easily rip out your gall bladder.