Haven't exactly gone up to everyone I know at some point and asked them this.
( I'd probably be stoned if it came up )
Still, I find it odd that no-one I know can do it.
It's separate muscle movements than wiggling your ears.
It almost always works to un-pop my ears if in a plane.
Also helps if I have water in my ear.
I hear little clicks from both ears and the clicking sound is like a tiny version of when you crack you knuckles.
If I hold the muscles used tense then I can hear my breathing loudly.
Anyone know what part of my ear I'm using / abusing