In Lego fandom, the acronym "POOP" stands for "Piece Out of Other Pieces".
A POOP - adjective form, "POOPy" - is a single Lego piece that is larger and more complex in form than it should be.
Lego is all about putting pieces together. POOP gives you single lumps of plastic that should have been multiple pieces.
This concept needs a little clarification.
Almost every Lego piece bigger than a fingernail could, in theory, be made from smaller pieces. You also need some large-ish pieces to build larger models, or you'll end up with a creaking mass of tiny pieces that's aching to fall apart.
So nobody's arguing that every 16-stud Technic beam should be replaced by two 8-studs or four 4-studs. And, obviously, big flat baseplates of whatever type need to be big and flat and all in one piece.
And the old spring-loaded crane jaws may be one irreducible assembly which has only one real purpose, but that purpose is one that'd be very difficult to achieve with separate pieces. Fair enough.
POOPy pieces, in contrast, don't have any good structural reason to be that way. And when a piece's POOPiness makes it less generally useful and more forced to adopt one specific role - and, moreover, reduces the time you can spend having fun building a model - then there is grounds for complaint.
Apropos of which, I think I have found the single POOPiest, and therefore just plain worst, piece that Lego Group has ever managed to make.
And here it is.
It's the astounding #30295 Car Base.
And yes, it is all one piece.
I bought it as part of an eBay job-lot of odd pieces, including six of the unusual Car Wash Brushes, plus a couple of axles for them, but no holders.
My Car Base is in the old dark grey colour, which means it had to have come from a Rock Raiders Chrome Crusher or Loader-Dozer. I also got one orange piece #30619, indicating that the very POOPy #4652 Tow Truck had contributed to this lot.
The Car Wash Brushes are a fine example of very unusual Lego pieces that're not POOPy at all. They're made from a translucent hard rubbery polymer, do not resemble any other Lego piece I can think of, and appear to be quite specialised in purpose. But they can actually be used for all sorts of odd Technic-y things.
Lego themselves only ever included the Brushes in car-wash or street-sweeper sorts of sets, plus the instant-classic 10184 Town Plan, which features on the box the boy who, one or two years earlier, appeared on the box of set 248.
But if you want to make, for instance, a Lego printer or plotter, Car Wash Brushes may work a lot better for certain sorts of paper handling tasks than the plain old tyres that you probably first thought of.
The brushes would probably work very nicely in a Lego Roomba. They can also engage each other like fuzzy gears. So even though the brushes have a smooth, not cross-axle, hole in the middle, I'm sure some lunatic's found a way to use them as part of a torque-limited or variable-shape transmission.
None of this can be said for the #30295 Car Base.
It's a Car Base, and that's all it is. You'd have to work quite hard to get it to do anything else, if you didn't just use it like a flat plate in the middle of some other construction that managed to avoid interfering with the Car Base's wheel-studs.
POOP is similar to the concept of "juniorisation", in which pieces are amalgamated to allow the very young, or very stupid, to build large Lego models without having to deal with any, y'know, thinking.
For a while, Lego had a terrible case of POOP/Junior Disease, producing sets with more and more big single-function pieces in them. You'd find something that looked like a normal little Lego set, which in the olden days could be expected to have at least fifty pieces in it. Then you got it home and discovered that there were actually only 28 pieces, because the whole chassis of the vehicle was one stupid piece that could, and should, have been made from several separate components.
But as this interview with the current CEO of Lego makes clear, the company has now scourged itself with barbed wire and abandoned these degenerate ways, returning to the True Path of lots of smaller pieces that you can do whatever the heck you want with.
If the fun of building is not why you're using Lego - if, for instance, you're using it as a rapid robot-prototyping system - then you'll probably be able to find a use for at least a few giant POOPy pieces.
To everyone else, they're an abomination whose death we should celebrate.
