Final answer:
The act of covering a train with graffiti is commonly referred to as train tagging or train bombing. It is an art form associated with the hip-hop and street art culture.
Step-by-step explanation:
The act of covering a train with graffiti is commonly referred to as train tagging or train bombing. This art form originated in urban areas, particularly in the 1970s and 1980s, and has been associated with the hip-hop and street art culture. Train tagging involves spray painting or creating elaborate artworks on the exterior surfaces of subway cars.
Train tagging has gained recognition as a form of artistic expression, although it is often considered illegal due to the vandalism aspect of graffiti on public property. Nonetheless, there are artists who embrace train tagging as a way to showcase their skills and creativity.