Sides of buses
The Good Doctors have drawn a correlation between the fact that a movie that is advertised on the sides of buses (both double and single decker) is likely to be of a lower quality than those not advertised in such a way.
Once listeners began to cotton onto the theory, they began contributing their own conclusive evidence. Mark rebuffed some but conceded that "Spider-Man 2, which I liked, had massive bus advertising - but then again, so did Sex Lives Of The Potato Men." Colin Murray suggested that the rule be changed to "no good comedies are advertised on the side of buses," but frankly, who cares what he thinks.
Andrew Collins noted that The Ugly Truth was heavily advertised on the side of buses, and that seeing it there was the best way to see it.
Son Of Rambow then also received heavy bus advertising, conclusively shattering the rule forever, in much the same way that Red Dragon smashed the Philip Seymour Hoffman rule.
When The Fourth Kind was released in 2009, Nigel Floyd described it as a "side of bus movie" because it was a film whose existence he was aware of because it was on the side of a bus. Floyd liked this description so much that he told Mark Kermode not to use it - only for Mark to shoot back than in fact the Sides Of Buses rule had already been invented by his listeners.
Also the source of some amusement when the posters are installed incorrectly - the prime example being a Fifty Shades Of Grey poster that ended up reading Fiftys Of Grey Hades. This was deemed to be a more accurate description of the film anyway.