1. Plosive sounds. 2. Prolonging the first part of the word or just the sentence in general. 3. Depends. If i know them, and they have been around me for a while, I will straight up tell them hey wtf dont do that shit. Tilting head and squinting eyes judgmentally is another favorite. If they don't know me i'd just tell em not to do it please. 4. Please don't write with these things - - - between sounds. Like A-a-a-apple. I feel like it's cliché. We've seen it. It"s been done. It had it's moment. I'd much rather people just described how it was said. Like, in an escape scene, you write “Are you sure Adam is okay?” he said catching his breath. I'm pretty sure nobody writes “Are you, huh, sure, huh, Adam is, huh, okay?” Trying to emulate breathing patterns (breath is an important part of stuttering/stammering btw).