A hog on ice: Charles Funk expended great effort in an attempt to trace the expression. He could not find a definite answer, but concluded that it probably arose in Scotland from curling terminology:

Hence, though my conclusion cannot be proved, I think that sometime during the the early centuries of the game, perhaps by accident one of the awkward, heavy stones did not have enough momentum to carry it to its destination and it stopped halfway along the course. I think that someone made the suggestion that it be allowed to stay there as an extra hazard, and I think that, because of its unwieldiness and its inertness, becoming party frozen into the ice, some player with a sense of humor likened it to a hog -- and the name stuck. If this hypothesis be correct, then the very fact that the stone occupied a central position, showing no regard to its interference with subsequent players, like an automobile driver who "hogs" the center of a road, made it appear self-assured, cocky, and independent, and thus gave rise to the humorous simile that came down through the centuries.

PS - has anybody here besides me ever curled? Bean? BelM?