Normally people found in high schools during lunch,
they stand with a group of friends pretending that they're "hanging with them" while in reality they aren't saying anything and add nothing to everybody else's fun. They most likely don't have any real friends to hang out with.
Another variety of loose change is rolling change, where a group of friends are walking and the loose change is following behind them.
During the first week of high school, I was loose change to the football team.
"Dude, look at William.....he's just rolling change to those gangsters walking around the South gym"