An exclusive group of individuals which have engaged in intimate encounters with strangers while on board a passenger train, most commonly in the bathroom compartment of the train; similar to the Mile High Club.
Gloria met a very special gentlemen on board the 4:15 Amtrak from Penn Station to Providence last month, and she was delighted to have joined the Third Rail Club with him. He still hasn't called.
by BostonBaller September 11, 2009