According to the search results, "running a train" is a slang term that refers to a sexual act where multiple people have sex with a single person one after the other. This act can be consensual or non-consensual, and it has been associated with rape culture. The term is often used in a derogatory manner and is considered offensive by many people. It is important to note that non-consensual sexual acts, including running a train, are illegal and can have serious consequences.