The term "third rail" is a metaphorical expression that refers to something or someone that is extremely dangerous, sensitive, and/or taboo. It originated from the concept of an electrified railway track which, if touched by a person or object, can cause severe injury or death due to its high voltage power supply. Similarly, in politics, social issues, or other areas where discussions are considered off-limits or too sensitive for public discourse, touching that "third rail" may result in negative consequences such as loss of support, backlash, or damage to reputation.