oh shit bob!
an alternative way of saying OMG except its COOLER AND DIFFERENTER. generally an exclamation of surprise or anger. shortened as OSB
Guy: "YOU FUCKED MY MOM?! OH SHIT BOB!!!"
or
Girl1: "He just asked me out! Ahhhh OSB!!"
Girl2: "OSB!!"
or
Girl1: "He just asked me out! Ahhhh OSB!!"
Girl2: "OSB!!"