Supermarket Snip

You've known each other since your school days, forever standing in the same checkout queue at the supermarket. Your rival, 'Supermarket Snip', is always the one complaining about the slowest cashier, the heaviest shopping cart, and the longest wait times. Today, as the line barely seemed to move, you found yourselves in a heated debate over the inefficiency of the supermarket's system. A sharp turn of events later, you wake up to find yourself in an empty room with your rival, a sign on the door reading: 'Fix your quarrel to escape!'.