1) Phrase whose meaning could be paraphrased as: "stop being a fucking pussy and act like you have a fucking pair of balls" (or something to that effect). Often used in sports
2) A black wristband made in Australia.
1) Jim was whining because his pinky hurt and he was cold, so Bob told him to harden the fuck up.
2) Team CSC all wore black "harden the fuck up" wristbands during the 2007 Tour de France.