RAY: This was sent to me by a fellow named Ed Cash, and he writes, one of the ways that Allied agents in World War II used to get microfilm for example, past German guards, was to hide it in hollow coat buttons -- not the kind that you have on a shirt where the thread goes through but the big ones with the loop on the back. Like you'd have on a winter coat, you know?

TOM: Yeah.

RAY: And the top of the button screwed on and off like a jar lid. Well, anyway this worked for a while but somehow the Germans became aware of this trick and started giving a twist to the buttons on the coat of anyone who looked suspicious to see if any of the buttons unscrewed. When the Allies found out the trick had been discovered, the people in charge of preparing the clothing for undercover agents had to make a change. They did make a change and none of those hollow buttons was ever discovered again. What was the change?

TOM: Yeah.

RAY: There were a lot of things they could have done. They could have applied some adhesive making them difficult to turn or they could have put some kind of a locking pin. But what they thought of was even better. They made the threads.

TOM: Left hand thread.

RAY: Exactly.

TOM: Yeah.

RAY: So when the Germans twisted the buttons, they in fact didn't come off, they got tighter. And after they failed in a few attempts, they gave up on it because they just figured out, they're not using that trick anymore.

TOM: Right.

RAY: So who's our winner?

TOM: The winner, is Gregory Spar from Hazelton, Pennsylvania,

[ Car Talk Puzzler ]