The performer shows a bottle or can and a glass and begins to pour a drink. He then removes his hand from the glass. The glass remains suspended in mid-air while continuing to fill with liquid. The glass and bottle/can are then separated. The performer toasts the audience.
You are supplied with a specially gimmicked bottle/can and glass. The special bottle/can allows you to easily float the glass and control the flow of liquid. Food colored water may be used if desired to simulate a drink. This is a wonderful effect, using beer it shoud be done with adult audiences.
The picture might not show the exact bottle or can that you are buying.