When a female goes to the male bathroom, and then picks up the toilet seat, and has her period in a counterclockwise motion on the lower part of the toilet seat, thus making a painting. Note, this must be done in a clockwise motion on National Holidays.
If a male does this with urethral bleeding or anal fissures that are in stream form, this is called the South Korean Sunset.
Roommate: DUDE, A GIRL JUST LEFT A PERIOD PAINTING IN THE BATHROOM! SCORE!!!