To "run a train" in sexual terms means that a group of men wait to have sex with one girl. Usually it does not qualify as a train unless there are more than 7 men involved but the term train is used to describe any number that is more than 1 with a female. The female has sex with a man and after he cums another man enters the room to have sex with the female and so forth. It is only considered a train when the woman is fully aware of the situation and allows for the men to have sex with her. Otherwise it would be considered rape.

Differs and is often confused with gang bang. Train involves sex with one person at a time while gang bang is when a group of males having sex with a female at the same time.

Something Bruno Mars would jump in front of.

Where a group of people line up and have sex with a person.

Many people having sex with a woman, fucking her like a train.

To be "on the train" means to be single and in pursuit of someone to spend the day and/or night, without the intent of perusing a relationship with that person.

On Valentine's Day the only way to "get off the train" would be to find a date, to give up in the pursuit of finding a date or when the clock strikes midnight and you're all alone.

Related: To be on the desperation train / To be on the train of despair / To be riding the train.

Often spoken on the phone, when simultaneously also on the train.

1. The act of performing a non-routine sex act on a partner to demonstrate that it will be expected or required later in the relationship. This term is frequently used in conjunction with specific societal roles or fetishistic kinks.

2. Gradually introducing a sexual act or sexual object to prepare the recipient for a new routine.