how could you say "No" to that?

It's real easy, Cap K. Put your tongue up behind your front teeth, completely closing off the escape route for air in your mouth leaving only the nasal passages and lips open and breathe out with your vocal cords vibrating. After a fraction of a second of this, open your mouth by pulling your tongue back and down and rounding your lips. You can stop any time you want but more than a second of producing sound would be considered excessive.