Hold the cap between both thumbs and both pointer (index) fingers, as shown below. Make the „Y“ shape with your thumbs and position them to show only the small, top, triangular section of the acorn.
Constrict your lips a little and blow hard, just as if you were blowing out a candle that was 3 feet away from you. The knuckles of your thumbs will rest right in between your lips. The thumb knuckles won’t get past your lips into your mouth, though, because your lips are pursed.
Get an acorn cap
Put it between your pointer and middle finger like this
Squeeze you hand in a fist like this