The act of watching video footage or witnessing vehicles that are equipped with train horns and watching videos of them in action.
Yo look at that honduhh scaring the crap out of the people in the parking garage!! That's horn porn right there!
1 more definition
the porn that they advertise on tv. For example, "call now for free sexy singles in your area!"
Man I got home so late last night and all I wanted to do was watch some tv, but there was nothing on except for fuckin horn porn commercials.