Passenger, often inexperienced flyers in Kettle Class, who crowd around or line up at a gate at an airport completely blocking the boarding area and preventing First and Business Class passengers from being able to get on the plane when they're allowed to. They can also cause delays and confusion if a passenger in a wheelchair needs to board as the chair has to plow through the mass of gate lice hovering around the gate.
When it's time to board, they have to be shooed from the front boarding area to the back of the line, delaying the flight for everyone.
"We should probably head to the plane early before the gate lice show up".
"I don't understand why those people were being gate lice. Don't they know Zone 4 means you board last ?"
Can be used to refer to all of Coach/Economy Class on a plane but usually used to highlight those passengers on an flight who, through their behavior, make it very apparent that they aren't familiar with how to get around at the airport, get through security or get on a plane without delaying or inconveniencing everyone else.
Typically they are from flyover country.
"We left 30 minutes late because there were a bunch of people back in Kettle Class who couldn't figure out how to get in their seats"