Usually people do this when they’re startled into asking a question. I’m curious as to how we find an answer like “Sure. Fine. Go ahead.” acceptable when it’s uttered all in the same breath. Saying only one of the words in the three listed would provide the same effect as a “yes”.
Also, it works when someone’s trying to say no: “No way, uh-uh, not now, not ever.” Perhaps this is done for emphasis, but other times it’s just excessive.
…I like instantaneous feedback. It makes me warm inside.
Let Abundantly Confirming Or Denying Something Die