I was looking into urban legends and I found one that was amusing to me, both by the outrageous claim and the fact it brought back a very old memory. The tale was that of a penny, having been laid on a train track, derailed a train form its fixed course. This story was proven false and is very entertaining, the thought of a single penny vs. a train is quite humorous.
The claim is extraordinary, and extraordinary claims require extraordinary evidence. Using that scientific thinking principal we can easily reject this claim. If a penny could really derail a train you would be hearing about the dangers of coins on the train tracks in the news, and these dangers would be common knowledge. I have laid many pennies on train tracks and was never told of any such news story or witness such an event.
Other things have been laid on train tracks, such as bricks, that have derailed trains. This leads to the ruling out of rival hypotheses principal of scientific thinking. When this myth started there was probably one occurrence of something that was on the train tracks. It could not have been a penny, but there may have been a penny on the track as well as a much more sizable obstacle on the tracks.