TLDR; Yes, anger gets your brain out of the way and the words tend to just flow. I'm almost 40 and yes, over the years, getting angry was the first point where speaking to someone I didn't know was completely fluent. In my experience, anger gets the thought process out of the way and you're just spewing words. Singing creates a cadence to the speech which falls in line with all the speech therapy that I ever had, breathe control, patterned speech, etc. The big revelation was when I figured out that I only stutter in my own voice. I got interested in learning about other accents and dialects back in the early 2000's and realized that if I used any accent other than my own, I never stuttered, I think it's similar to singing, putting the focus more on "how" you're speaking rather than "what" you're speaking. So when I was working at Wal-Mart, and had to get on the overhead speaker to call for a manager, I would use an over the top Scottish accent and it worked like a charm, I'm sure it was more than odd for the customers down here in south Louisiana, but it worked and that's all I cared about. More recently, like the last 5-8 years, I have moved into a role at work which requires me to be on a lot of meetings discussing software designs, it was rough at first, but as the confidence came the stuttering faded and now I rarely stutter except for high stress situations or with perceived authority figures.