With a pawnbroker you can sell an item outright but 'in hock' implies the other way a pawnbroker works in that Tommy would have given his guitar to the pawnbroker who would have loaned him some money and kept the guitar as collatoral. If Tommy doesn't pay back the loan within an agreed time period then the pawnbroker keeps the guitar and can sell it to get back the money he loaned Tommy. The amount of the loan (inc interest) is usually less than the selling value of the pawned item, or the pawnbroker would lose out on all non-redeemed items.