This idiomatic expression can describe any kind of movement, but is especially linked to running. A scalded dog would be moving as quickly as it was capable of doing, and it would be motivated by pain and fear - that combination makes for some serious speed.
When the banditsaw the police coming, he ran faster than a scalded dog.
Ever see a cat lick its ass? Then you know it's pretty damn fast.
When I heard my old man coming home right when I was in the middle of some afternoon delight with my next door neighbor, he gathered up his clothes, rock-hard dick and all, and jumped out the window faster than a cat can lick its ass.
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.