What did a kid behind the heffleys do in the security line at the airport?

The Diary of the Wimpy Kid: The Getaway was about the Heffley’s decision to skip Christmas by going on a trip by plane to Isla De Corales but encountering a series of mishaps. One of these was when they enter the line for security, the kid behind the Heffleys unclips a barrier separating the lines, causing everybody to scramble.