Similarly, cracking knuckles was a mystery until Dr. Adrien Flatt (hand surgeon, U of Iowa) took scans of a knuckle being 'cracked'. It was bubbles in the joint fluid being squeezed out of the compressed joint back into solution.

Hey! I wonder if that action produces similar accelerations?

now I get to feel like a pistol shrimp every time I snap.

Ha. That was the first thing I thought of when I read this.

How fast does the end of your tongue/lips flicker when you blow a raspberry?

Assuming 2mm deflection and 20 Hz raspberry:

2mm ⋅ (2π⋅ 20 Hz)^2 ≈ 32 m/s^2

Unfortunately this is linear acceleration and thus not directly comparable to the 1.6 × 10^6° / s^2 (or approximately 30,000 radians per second squared) angular acceleration that the researchers recorded.

I thought it was a sneeze.

Perhaps, but that's not in scope of this study:

> a snap of the finger produces the highest rotational acceleration observed in humans, even faster than the arm of a professional baseball pitcher.

Money well spent.

Ig Nobel Prize right here