And another thing--

The Hitch-Hiker's Guide To The Galaxy - the encyclopedia, not the novel - has a lot of information on sequels. For instance, we can read about an expert on robot construction on the planet DNA Prime, who gained fame for a series of five robots often considered the best in their class. They could do tricks, tell jokes, spin absolutely insane stories that still somehow seemed to be about regular people, and were generally just really great to hang out with. (Even if some people claimed that the last robot was pretty depressing, and not in a fun way.)

Sadly, the famous robot builder died before he could build a sixth robot to repair the fifth one, so after a suitable time, his widow hired a successful builder of toy robots from the planet Eringo Beta to build it instead. He quickly dug up the blueprints for the first five and got on it.

After several months of hard work, he presented the result to an excited crowd. At first, many remained cautiously optimistic; sure, the bodywork was patched together from parts that he'd copied from the five original robots without adding anything new, but they were sure that once he switched the robot on, it was bound to do something entertaining.

He hit the switch.

"Fffffffffroody," said the robot and moved its left knee a bit. (The knee had been a small detail on the third robot, added mostly as a joke, but was now supposed to carry the whole construction.) "Frood. Froooody." It paused long enough for the more fanatical audience members to remember that one of the old robots had indeed used the word "frood" at one point, though it now seemed to make up the new robot's entire vocabulary. "Frood," it added as if to underline this, as a small plume of smoke started rising from its head. (The head, which had been many people's favourite detail in the first five robots, didn't do much at all apart from this, except have a cup of tea now and then.)

The robot builder was, understandably, starting to panic. None of the parts he'd copied from the old robots seemed to be hooked up to the motherboard as they didn't actually do anything, and it was becoming clear that building the entire frame from little throwaway details with no strong structure of his own was a Very Bad Idea. "Uh... um... hang on," he called and ran into his workshop to retrieve an extra part (made from open source technology that everyone already knew) which he attached to the robot's back. The robot, which had only been balanced to stand perfectly still and impress with its mere existence and official Sequel status, immediately tipped onto said back with a hollow "bong" and lay there perfectly still, frooding quietly to itself, while a part from the fifth robot which had never worked right in the first place made a high-pitched whining noise.

One by one, the audience filed out. In the paper the next day, the new robot builder was dismissed as an "epp", which is Betelgeuse slang for "probably a great guy if you buy him a pint, but who doesn't seem to have any clue about building this kind of robot and should probably have let us keep our memories of the old ones intact."

And if you think that joke is old, stay the hell away from And Another Thing... .