I just don't think you'd be able to recreate the feelings of anxiety that come from blocking or stuttering. I'd be pretty peeved if someone was pretending to stutter to me while I was at work. There is an app that makes non-stutterers stutter by replaying their words through headphones, and it messes with the ability to speak fluently. Interestingly, the app doesnt work on stutterers. Maybe that would be more analogous than pretending to stutter, which is what it sounds like is being asked.