A phrase your grandparent might use to describe being busy with a futile, impossible, or endless task.
Cats like to cover their feces, but if they've done their business on a frozen pond, no matter how long they try to dig up something to cover it with, their paws will always slide on the ice. The joke is the mental image of a cat making the digging motion on ice for a long time.
I don't know why I keep weeding that garden. I've been busier than a cat trying to bury a turd on a frozen pond, but I tell you what, there's gonna be just as many dandelions tomorrow.
Fogey/fogy /fougi/ sl. (early 18C+, orig. Scot) old-fashioned, stuck-in-the mud.
Person with old fashioned ideas which he is unwilling to change: Come to the disco and stop being such an old fogey!
You think me an old fogeyand an old tory, his thoughtful voice said. I saw three generations since O’Connel’s time. I remember the famine. Do you know that the orange lodges agitated for repeal of the union twenty years before O’Connel did or before the prelates of your communion denounced him as a demagogue? You fenians forget some things. (James Joyce, Ulysses. Penguin Books,1992. p. 38)