Expressionisms: “Blowing Smoke Up Your Ass”

I get some expressions. Like the one below. Apes sometimes throw their feces. If you’re acting crazy, it could be said you are acting like a monkey, and, symbollically, hurling feces. This one makes no sense. If someone were blowing smoke up my butt, I’d not only wonder what I was doing wrong, but also wonder why no one else was stopping this other person from doing something else wrong to me.