If your dentist begins asking you this question it's time to scream. Then run. Run like you've never run before!
Laurence Olivier's character in Marathon Man, a former member of the (German) SS (and a dentist), is convinced that Dustin Hoffman's character, a marathon runner, knows whether or not it is safe to pick up something from a safe deposit box.
When Hoffman's character protests his ignorance, Olivier gets out the drills ... but not the anesthetics. The scene which contains this one simple question is one of the most agonizing and disturbing torture scenes ever filmed.
Is it safe?