TabbsTheBat

What in the fuck? Never seen that, but I wouldn't bother at that point

1. Place your thumb firmly onto your middle finger, you'll want to apply significant pressure with your finger here
2. Push your thumb ourwardly to the side while maintaining pressure
3. As your middle finger slams into the palm bit of your thumb it should produce a noise
4. Practice until you can do it more consistently and loudly. Try doing with the other hand - I can only snap loudly with my non-dominant hand

Sorry man, you'll have to sacrifice your wife to the elder gods to find it, there's nothing else that can be done :(

/j