From TomDeMarco's book ControllingSoftwareProjects:
If you were eating in a restaurant, and you saw a cockroach crawling up the wall, you probably wouldn't say,
"Oh look, there's the bug. Good thing it wasn't in our food."
Rather, you'd assume that the place was infested.
Actually, if a restaurant were software, we'd walk in expecting it was infested. Naturally, if we didn't see a roach until dessert, we'd say, "Oh look, there's the bug. Good thing it wasn't in our food."
A software engineer would say, "Let's move to a different table and see if it happens again."
That's not a bug, it's a dessert!