Does any of you know what this strange anatomical feature is actually called and/or how to fire it at will?
But, strangely enough, a handful of friends and I discovered this anatomical feature when we were kids...maybe seven or eight years old...and developed it to a pretty predictable art form. We called it "skeet". Which, in modern/adult terminology means something altogether different (though also involving bodily fluids). I haven't done it, or tried it, in over 20 years. So the ability seems to be completely atrophied, but I remember what it felt like now that I'm thinking about it. I reckon I could make it happen again with a bit of practice.
And, so I don't actually know how to tell you to do it at will, but I know it can be done, because I've done it, and seen a few other kids do it. Some were better than others (much longer range, and dramatically better accuracy), but I don't know if that was a factor of more practice or if some people are built significantly different.
Anyway, if a bunch of seven or eight year olds can figure out how to do it without guidance, I'm sure a grownup with a hackers mindset can handle it.