An exclaimation, generally used to describe either something surprising or something extremely cool, radical, awesome, or any other adjective from the Ninja Turtlevocabulary.
When something surprising with a huge magnitude happens (IE: Pregnancy, The rapture, and/or Bon Jovi making a serious comeback) this phrase is used to express disbelief
Man #1-Hey did you hear the latest Nickel back song, its pretty good
Guy #1: I didn't think Palin was so bad. Why didn't you women vote for her, anyway?
Girl #1: Sweet polevaulting Jesus, Caribou Barbie was the ultimate parody of a token! I don't know where the Gay Old Pedophiles find these incompetent candidates. She's tundra trash at it's worst, pimping out her office and family like she did.
Guy #1: OK, OK! Settle down!