When you begin by gently fisting your partner, imitating the connecting road of a steam train(link from the engine to the wheels). Slowly picking up speed much like a train itself. Once you have reached maximum speed you can manage, you yell CHOO CHOO, spouting two glorious arks of semen vertically in the air to mimic the puff of steam.
I Choo-Choo Trained my girlfriend so hard last night, she loved it, she didn't stop screaming the whole time.
A group sex activity where four males use their penises to form a cross around a female's breasts and the female uses her feet, mouth, and one ear to stimulate male ejaculation from all four parties.
The act of defecating on ones chest while wearing a conductors hat and having them yell "CHOO CHOO" while strangling ones throat and having ones canine observe.
John and I were making love when I suddenly felt a warm substance on my chest and I heard him yell "CHOO CHOO"!! I think he just performed a "Chocolate Choo Choo Train" because he was wearing his conductors hat and he made my dog Nibbles stay in the room.