Usually coups are perpetrated in countries with very weak governments, such as in West Africa, Bolivia, or Southwest Asia. They get progressively worse (i.e., more violent, more prolonged, and more repressive) until eventually some junta builds up protection against against the next coup. This is what happened in Iraq after 1979; it happened in Syria in 1973; it also happened in Japan in 1607. In other cases, the coup accomplishes its goals (Chile 1973) and retires as a PR move.
After a coup occurs, the military leadership is known as a junta.
Military coups are difficult to pull off and usually are nipped in the bud. Even with foreign assistance, they are hard, because they are a form of high-speed civil war.
Inter-class violence often comes with a coup d'etat.
Female: "Didn't he start the coup d'état back in the 70s?"
Dude 2: "Yeah, I'm not sorry that guy is dead, had my uncle killed."
Dude 1: "Fuck your communist tree loving fag uncle."
b) When a government is discredited by its' actions enough for them to be forced by thier people to hand over power, since no-one is listening to them
Sarah: Dude, I was watchin the Cardinals game last night with the homies, we threw down hella beer and then got some mexican food from the TL...that shit did somethin funky to my stomach this morning...my ass took the 15th floor bathroom over this morning, it was like a coup d'etat...i went in there with a machine gun, and came out with no prisoners...it was modern warfare 2 in that motherfucker