Rob is blowing a whistle, over and over.
Bob: “Why are you blowing that whistle, Rob?”
Rob: “To keep the dragons away.”
Bob: “I see no dragons.”
Rob: “It works!”
Rob is blowing a whistle, over and over.
Bob: “Why are you blowing that whistle, Rob?”
Rob: “To keep the dragons away.”
Bob: “I see no dragons.”
Rob: “It works!”
Pretty sure they showed on Mythbusters that tapping the side of the can is actually much more effective. The reason is that bubbles form all around the edges (and top) of the can and they cause the massive bubbling up when the can opens.