The scene is sometime in the old era when cockpits had round dials plus flight engineers and navigators.
The crusty old-timer captain is breaking in a brand new navigator. The captain opens his briefcase, pulls out a .38 and rests it on the glare panel.
He asks the navigator, "Know what this is for?"
"No, sir," replies the newbie.
"I use it on navigators that get us lost," explains the captain, winking at his first officer.
The navigator then opens his briefcase, pulls out a .45 and sets it on his chart table.
"What's THAT for?" queries the surprised captain.
"Well, sir," replies the navigator, "I'll know we're lost before you will."