"Hillbilly and mothballs" joke

A hillbilly's old wife sent him to town to get something to rid the place of moths that had troubled them. The druggist sold him a box of mothballs.
Months later, the hill man came into the drugstore, complaining that: "Them mothballs wouldn't work nohow, noway. Marthy and me we aimed carefully, too. But we ain't hit a single moth! Maybe you got a bigger size, like one of them pool table balls."