A few nights ago my son-in-law and I were smoking on the back patio and I noticed he was putting his thumb on top ot the bowl and raising it up and down as he smoked. Kind of regulating the flow of air. He had a massive billow of smoke. I asked him what he was doing and how he came up with the technique. He said he was watching old Sherlock Holmes shows and saw him doing it so he tried it. I didn't start smoking yesterday but I have never encountered this. Have I been under a rock? Who else does this?