A boy asks his grandpa

 In the distant future of 2010, a boy asks his grandpa, "Grandpa, what's a line?"

The grandpa replies, "A bit over twenty years ago, there wasn't enough meat in stores, so we had to wait in long queues at the stores' entrance in hopes of there being some meat for us to buy. That's what lines are. Understand?"

"Oh, okay," says the boy. "But what's meat?"