Tee Hee. Just goes to show, even with great flexibility, a poor technique can always spell disaster. It may be worth researching the term "blowjob". HTH
Show me a decent source and I'll believe. Hardly blummin' highbrow. Added this; I've now read the article and your synopsis of it is wrong, not the article.
Assuming you snap with your thumb and middle finger, stick a bit of fabric or something where your ring finger touches the base of your thumb then snap. The sound is heavily muffled, showing that that's where the "snap" sound is produced.
The article is right and it's very similar to how you and Supertyke described it. It's just that your finger snaps down on both your thumb and your other fingers and it's the air rushing out from the gap between them that makes the snap. What that article doesn't do is back up how Mr C describes it. Quite the opposite.
The more I snap, the more I feel myself bending to the Fry camp. I can do it without slapping my palm, but it's not the same.