there's a kid at my local safeway that's a dead ringer for this guy, although the skull is not quite so fucked up.
The line mentioned by Zen may be a mask, but more likely is the product of some (largely unsuccessful) surgical intervention early on.
The link to Crouzon's Syndrome explains the need for some surgery to prevent blindness.
Either way, while I am a (somewhat) mature adult, I am ashamed to admit that I try and choose a checkout line different than the one in which Timmy is working, so I will not have to stop myself from staring in horror.
(perhaps I can cross post this to the neighbourhood thread)