The space between your helmet and your goggles exposing your forehead while skiing. Extremely bad gorby gaps can show over an inch of forehead, and sometimes even have strands of hair falling over the person's goggles. Gorby gaps can be caused by a bad fall, or the person just not knowing any better. A good skiier can get a gorby gap and will be laughed at, but gorby gap is almost always seen on a Gorby.
"You just packed crap dude, you better fix your goggles you've got a gorby gap."