This is Skyrocket Toys' Candy Craft Chocolate Pen, due out this fall (just in time for Christmas!) for around $30. It uses an electric motor to extrude liquid chocolate that quickly hardens into the shape of the penis you just drew. Now, before you start complaining about how big the pen is(!), just remember it has to be big TO HOLD ALL THAT CHOCOLATE. Obviously, I have every intention of being the first person to write an entire erotic novel in chocolate. "Already been done." DAMN YOU, WILLY WONKA.
Keep going for a video of the pen in action.
Thanks to MisterP, who writes in chocolate the old fashioned way: leaving a bag of flaming shit on the doorstep of an enemy. Oh man, a bag of flaming shit is worth at LEAST 4,000 words.