You carry around a top-heavy backpack-like thing, which supports a pair of parallel masts, a pair of speakers and a discreet projector nestled into the back of your neck. A touch of kyphosis is helpful here.
The actual sail is a plain white sheet spread between the masts, and the projector projects
on to it.
The projector has to be digital, not a real film projector, because it has to be able to compensate for the angle of the sail, and any slack in it, which it can do because it can 'read' the positions and angles of the two masts.
The whole contraption is controlled from a hand-held iPod-like device.
The touch of a button allows you to display behind your own head, for the benefit of your interlocutors, a montage of film clips appropriate to your message. The speakers, perched parrot-like on your shoulders, may reinforce it if required.
For example, a short clip of Tweety-Pie panicking 'It de putty tat! It de putty tat!', cutting immediately to a scene of extreme violence from, say, one of the Terminator films, would in come circumstances make an excellent substitute for swearing.
Instead of self-recrimination, just flash up a brief image of Homer Simpson.
You could also do some useful silent sarcasm with this device.