Good grief! Is that some kind of a medical condition or is something squeezing this guy till his eyes pop out?
There are several people who can do this.
As far as I can tell, there are muscles that move the eyes forward and we all can do it a tiny bit.
These guys (and gals) exercise those muscles to do it a lot.
Like a weight lifter who can jerk 300 lbs, they are rare and remarkable.