when a person is high drunk or tripping balls, you talk to them and tell them about a box you have in your hands. Then you talkto them as you are putting the "invisible box" over there head. when the box is over there head, you move your mouth but do not talk, creating the illusion that the box does not allow you to hear. If done correctly the person under the influence will flip out.
My friend gave me the invisible box last night. I was so scared that i was deaf i almost ripped my ears out.