Thieves Cant has historical roots, and in theory, heavy roleplaying groups use it at their tables, which is actually pretty awesome. My group is not counted among that number, and that is fine.
I began reading this post at A Knight at the Opera and felt inspired. Then I finished reading the post and am thrilled that my inspiration isn't lifted wholesale from the post. Be sure to take the time to read that post though, as its worth it to Gamemasters of all stripes.
My default table rule for rumor tables is that each PC that begins a session in an urban environment gets to roll 1 + Charisma modifier (but at least 1) time on that area's rumor table.
Since larger towns and cities of all sizes have thieves' guilds - this is a fantasy game, after all - this means lots of people using Thieves Cant.
My new house rule is that rogues and others familiar with Thieves Cant get an additional 1 + Charisma modifier rolls on the rumor table, if only because the more interesting information, game-wise, tends to be known and whispered about by the seedier elements of the town.
This might cut in a bit on the bard's role as an information gatherer, but I don't really mind, as they still learn several rumors each time (is there such a thing as a noncharismatic bard?) and they can use their class-specific skills to focus on whichever rumor(s) the PCs pursue.
I like it because it doesn't require anyone to learn new slang unless they want to do so, and it makes it more worthwhile to be a rogue of some sort.
