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1. An audible warning device on a diesel or electric locomotive

2. The act of emitting a long and loud fart during an especially strong thrust when having sex.

In other words, farting while running train on someone
Dan and I were having great sex, until his eyes got really big, his cheeks got red, and then he train-horned on me. The smell wasn't too bad, but the sound really ruined the evening.
by derpyword15 December 03, 2016
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