- Done in Cars 2 between Holly Shiftwell and Mater — she identifies Mater as a fellow spy when he correctly answers obscure questions about the air cooling used by Volkswagen engines.
- In Captain America: The First Avenger, when Peggy takes Steve to the secret military lab, she has a casual conversation with an elderly lady about the weather. The elderly lady says "Wonderful weather, isn't it?" Peggy responds, "Yes, but I always carry an umbrella," which is the code phrase to signal that she is headed to the lab.
- Parodied in Agents Of SHIELD, episode 3:
Sky: Skipper to Bravo. I got eyes on Top Dog. The Eagle is landing.
Simmons: What are you doing?
Sky: Uh, sorry. I ... I dunno. I see Quinn, I'm gonna go talk to him.
- Played straight in "T.A.H.I.T.I.". When the team arrives at the Guest House facility, the guards greet them with "How was the ride from Istanbul?" None of them know the countersign, it's not in any of SHIELD's databases, and the guards refuse to say anything else. So, the team ends up having to fight their way in.