First of all, how could I possibly translate this into proper german words? The automatic transscript for this sounds ridiculous, So I am not going to translate that soon. Make it into a riddle: It´s something I do often, when I am alone at home. Only there I am free to express myself fully, in a calm and safe environment. If you see me flapping in public, it can be one of this two scenarios. First: I like you a lot and I trust you enough. Or second: I am under extrem pressure and need to flap to release tension.
Usually I am able to supress it. All of my expressions are dialed down, if people are around, that might not understand me.