I can put both my hands In a "pray" position behind my back between my shoulder blades. I can vibrate my eyes. Perpetually crack my right ankle. And pull my arm out of it's socket.
Oh shit. You just gave me a memo of middle/high school. I use to be able to do that. I just checked and maybe if I keep practicing, but it's not there anymore.
Someone I knew did it to me in school. Like just vibrated their eyes while looking at me. Then asked if I could do that. Well no, but it intrigued my young ass enough to figure out how he did it. He told me and after a few days I was able to do it pretty easy.
That's similar to how I learned! My brother could do it and I was envious and figured it out, he can do it for as long as he wants but my eyes tire after maybe 20 seconds or so