3) Hackers in the US figured out how to commandeer electronic road signs, leading to a spate of apocalyptic alert messages. Other versions included "RAPTORS AHEAD" and "NAZI ZOMBIES! RUN!!!".
1) Gatwick Express or drugged sloths? It's a close call. Spotted in March this year and posted on the Going Underground blog.
Damn... wish I thought of these first.
All wording stolen from here cause I'm LAZY today!