When you're using a secret language like, for example, thieves' cant to engage in message passing between your fellow party members under the watchful eyes of someone you don't want eavesdropping... first make sure they're not also a thief.

Transcript

Lando: Nice ship. It's mine now.
Han: Yeah, well, of course.
C-3PO: What?
Lando: He blew up my ship last time I saw him.
Han: Hey, that was a perfectly legitimate conflict of interest.
Leia: You brought us here knowing you would have to hand over our ship?!
Han: My ship, sweetheart.
C-3PO: How are we going to get out of here?
Han: Don't worry, we'll eal-stay it ack-bay ater-lay.
Lando: Art-smay inking-thay!