I'll explain that I'm actually thinking of a movie for the UI, and I want it to be as exactly like that as possible; I'm sure they get this request really often, and it won't be anything new to them; and I'll explain that I even brought some scenes from the movie to show them exactly what I wanted. And then I'll be grudgingly persuaded to pop in the relevant DVD...
And the scenes will be from a pirate movie, with an old-timey European pirate/bandit/mercenary chief writing with a quill on parchment while wearing a coat with ruffles and lace.
Only quills will work as pointing devices. To save your work, you sprinkle some sand on the tablet and blow it off. The tablet comes with a breathalyzer attachment, which checks for enough rum in the air to prove that you're a legit pirate but not so much rum that you're signing contracts while drunk. Voice input must be in Ebonics, which is pretty much what the Cavaliers spoke in the English Civil War. Voice output is in a thick Devonshire burr (the classic pirate accent) that makes you think that the app's probably half drunk.
Now, if only someone's eccentric enough to do it...