RIP is the acronym for "rest in peace". Rip is a verb with a lot of meanings. One of them says that if you let rip, you do something forcefully and without trying to control yourserlf, wich is informal. But they all convey with the verb tear.
Anyway, I could not pass it off, the idea that rest in peace is an action too. Why is it not a verb? I think it should. Sometimes life is full of a quite silence and you just stay where you are, as Fernando Milagros says you don not want to shot to protect yourself anymore. It happens when you are waiting for something does not come and you just stay there resting in peace, maybe dying into life.