A slur used by internet racists and homophobes. It stands for the four Gs found in two very offensive term put together to make a ridiculous still offensive term.
The original usage was more popular in the early 2010s, and used by YouTubers such as iDubbbz or 4chan users, but had apparently been shortened to get around moderation.
Brought to public attention by Bob Woodward and Carl Bernstein in the book on the fall of Richard Nixon, All The President’s Men, ratfucker was Nixon’s term for a political operative who sows chaos among opponents; an agent provocateur. It is thought to have originated among campus political rivalries at USC, and seems to have some usage in the US military.
Along with Nixon’s other ratfuckers, Roger Stone caused fights at otherwise peaceful Democratic Party protests to generate a false narrative that the Democrats were violent and dangerous.