When shitting process of motion comes, in between a bad event, for a person, this exclamation word id used.
No bad I expected for today, and rat! those liquid shits where in my pant!!
Morgan Freeman and 21 Savage said it best: "A 'rat' is a traitor, a conceiver, planner or physical participator. He doesn't sell secrets for power or cash, he betrays the trust of his team or his family hoping to save his own cowardly ass...The difference between a snitch and a rat is, at least a snitch is human, but a rat is a fuckin' rat, period" (Snitches & Rats Interlude).
A person who is stupid and doesn't have basic knowledge.
Person 1: I don't need to know about real world problems.
Person 2: You're a rat.
Someone who is manipulative and unable to differentiate between political operation and their personal life.
A rodent that is a larger version of a mouse, having a more pointed snout a sparsely hairy tail and various kinds are responsible for caring diseases. But many species are kept as house pets in many countries.