A way to add flavourful spice to your fictional roleplaying worlds is to adapt common sayings to use vocabulary peculiar to the time or setting.

Hold your hippogriffs! A lot of the time that actually sounds corny or just plain stupid. Be careful.

Transcript

C-3PO: I don't know where your ship learnt to communicate. There's traces of a peculiar dialect in there.
Chewbacca: So... what do you think of Princess, "Han"?
Han: I'm trying not to, pal!
Chewbacca: {softly} Good...
Han: Still, she's got a lot of spirit.
Han: I don't know, what do you think? Do you think an ex-Senator and a guy like me...
Chewbacca: Hmmm. One might say that I am a guy like you. Do you think—
Han: No!
Han: We're completely different! You're... like...
Han: Um... and I'm...
Han: Look, it's simple. We're as unalike as... as Camembert and Brie! {storms out}
{beat}
{beat, C-3PO looks up at Chewbacca}
C-3PO: {calling after Han} You're seriously having problems with that??