When a suppository is manually inserted with one's index finger (or more if necessary) into the anus and it is gently parked on the anal verge to all your friends' shock and horror.
"Oh my god Mandy I can't believe you keep ledging right in front of me; go and sanitise your poo-finger"
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.