An archaeologist is guiding students through a cave tour, identifying artefacts as they go.
He identifies a ball and explains its usage, the same with a guitar.
His students are impressed as they sip their Pepsi and an enthusiastic girl proffers another fossil. "What's this, professor?" she urges excitedly. Examining the long-gone Coca-Cola style bottle however, he is utterly baffled; "I've no idea!"