The grinding of MMORPGs spring to mind here. The next time one of my friends blows off a fun evening of imbibing fermented vegetable bi-products because they “have to” go skin two thousand mutant vampire bunnies in the Forests of Terrifying Cliché in order to advance their lvl 32 hippy gnome mage’s leather working skill I’m just going to push them to the floor and give them a comprehensive shoeing right there and then.