system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:What does middle finger sign actually mean? how did it originate?
gpt
The gesture dates back from Ancient Greece and Ancient Rome, as a symbol reminiscent of sexual intercourse, and was often used towards a people as a reference to "a male who submits to anal penetration." It's Latin name, *digitus impudicus* translates to the "shameless, indecent or offensive finger." 

It is said that it came to the United States via Italian immigrants, and was first documented being used in a baseball team photo when Old Hoss Radbourn flipped off the cameraman.

TL;DR: It is used to symbolize anal sex and originated in Ancient Greece.