Snap snap

I believe that's called "puppy play."

possibly pet play or hypnosis but definitely conditioning play

would recommend it's fun

either that or hypnotic suggestion

https://www.youtube.com/watch?v=bM7rBsVR0dg

Great cover of Prong here

It's when you bend your fingers so far back that the bones snap.
Pretty common in America, rather than the less painful 'clicking' made elsewhere.