Innuendo - Innuendo is to Bluff what Tracking is to Search. If you have a decent Bluff skill you can do a crude form of this skill, and in fact Bluff is the right skill if you want to communicate information to "over the head" of some listeners to your allies, but you have not established codewords or other support ahead of time. A real world example of the Bluff approach to this is to talk to someone nicely on the speakerphone while making facial expressions and gestures to indicate your true feelings to others in the room with you. Higher bluff would let you do the same, but your boss would think you were being polite while your team members would know you were being sarcastic.
I'm using Innuendo in the discussion below to describe a skill that does something similar but involves a shared code of behavior that is understood by a wide group of similarly informed people. Innuendo in this game is more properly "Earth People Court Language", and it is similar to the 3.0 edition skill (cha based, trained only, class skill for rogues and bards only, 5 ranks of bluff gives a +2 synergy bonus to generate the communication, 5 ranks of sense motive gives +2 synergy bonus to understand the communication).
There is a base difficulty which is tied to the complexity of the communication. The amount by which the person doing the Innuendo beats that difficulty makes it harder for a victim to notice, and easier for friends to appreciate.
Using a specific jargon adds +10 to your skill roll for encoding the Innuendo. Taking 10 in verbal situations and 20 in written situations is allowed. Each rank of Innuendo gives you an additional Jargon that you can use. Most users stick with taking 10 or 20, unless they're facing a victim that is more skilled than they are, and therefore there is zero chance they'll get the message across without pushing their limits of wit.
Jargon tends to be fairly specific:
Examples of Jargon: Street Legal, Street Illegal, Law/Lawyers, Court, Military Militia, Military Land forces, Military Sea forces, Hero Band (specific for EACH hero band, this is a private battle language), Mercantile Caravan, Mercantile Sea, Mercantile Middleman (warehousing and such), Mercantile Hospitality, Diplomatic (one jargon for each race, plus one for the Wild) , News (Legal), News (Underground)
All Imperial paperwork in the campaign is encoded in both written (take 20) innuendo and jargon.
Non-News/Diplomatic jargon is almost useless for concepts not commonly used (eg, Military jargon isn't useful for criticizing the wine provided by the host) and therefore provides no bonus...you have to fall back on "normal" innuendo. Remember though that this jargon only sounds like jargon to the Innuendo trained. To outsiders, the people at the tavern table are just gossiping about their family. To those with it, assuming only the Jargon bonus prevented understanding, they can tell that the group is having a highly technical discussion about something or other, but without the right jargon they won't know what (other skills could give clues, as 4 Aristocrats at a table will probably be having a different conversation than 4 Lawyers).
Diplomatic jargon is dress and body language cues that are quite subtle, chosen based on the target race's cultural focus (Dwarves, with their concealing beards, tend to overlook subtle facial cues, Gnomes, with their eccentric dress, don't think anything odd of rapidly shifting clothing among the embassy staff). Diplomatic jargon only works on the target race. Sea People and mixed Shining Court diplomatic groups cause problems for this kind of Jargon, as what will slip by an Elf might enrage an Orc, and the very different social cues in Seelie and Unseelie courts make use of this jargon tricky indeed. However if all present are skilled in ALL forms of jargon needed (Elf, Human, Orc for Sea people, Seelie/Unseelie for Sky), the bonus applies.
Sometimes clever people use jargon to slip something past the Imperial Censors. Many publications must be read at three levels....the "commoner" level (no innuendo), the Imperial level (whatever the censors approved) and the Deep level (whatever the author wanted to say that he slipped past the censors). As Innuendo is sensitive to target audience, a paper may read very differently to different subclasses in society.
You can't understand Innuendo without the skill and without the right jargon you're unlikely to decode it. However Sense Motive may give you a clue that something isn't as it seems. A perceptive Gnome might start getting uneasy every time the Embassy Staff used a lot of red in their dress, but woudn't be able to listen into the byplay without somehow attaining a rank in the skill.