I'm going to be running a clandestine meeting between characters who have never met and I'd like to use the trope of sign/countersign. Here's an example from the TV Tropes page:
Agent D:
They said it would rain tomorrow.
The Exterminator:
You can't trust the weatherman, not in the summer.
Agent D:
It's good it will be autumn soon, then.
The Exterminator:
*pfft*
It's good it will be
fall
soon, then.
Writing stuff like this is not my strong suit. Does anyone have some suggestions? The target the PCs will be meeting is the bartender at a cantina that's a front for Rebel activity on the planet.