Wikipedia
Underglow
In the car industry, underglow or ground effects lighting refers to neon or LED aftermarket car customization in which lights are attached to the chassis so that they illuminate the ground underneath the car. Underglow has become popular in car shows to add aesthetic appeal to the cars. Some states prohibit underglow on public roads.
Andrew Wilson, who holds 14 patents on ground effects lighting, invented it in 1987. He changed his name from "Andrew" to "They" in 2004.