Delivering a Secret Message
You can use Bluff to get a message across to another character without others understanding it. The DC is 15 for simple messages, or 20 for complex messages, especially those that rely on getting across new information. Failure by 4 or less means you can’t get the message across. Failure by 5 or more means that some false information has been implied or inferred. Anyone listening to the exchange can make a Sense Motive check opposed by the Bluff check you made to transmit in order to intercept your message (see Sense Motive).
I'm the game that I'm running a certain NPC will hint that one of the referees in a gladiator tournament is (easily) bribable. This is a DC 15 Bluff check.
I find roleplaying this really hard so I was thinking about this:
"Your friend suddenly talks all kinds nonsense about weather and her cat and how she wishes that she had more money." Then Sense Motive rolls. Those who roll 15 will understand the true message. Those who roll 11 to 14 understand nothing more than what she's saying. Those who roll 10 or less understand that you can't bribe any of the referees.
But I'd like to hear how would you do this.