Nasruddin is digging a hole to dispose of rubbish. What will he do with the dirt? Dig a hole to bury it. And that dirt? Nasruddin says, "You can't expect me to have everything figured out in advance."
Notes: In one version, Nasruddin does this for a new neighbor: there was a big pile of dirt left when neighbor finished building house, so Nasruddin decides to bury the pile of dirt as a favor.