Brodin Goes Shopping

One day, Brodin went to town to buy new clothes. First he tried on a pair of trousers. He didn't like the trousers, so he gave them back to the shopkeeper. Then he tried a robe which had the same price as the trousers. Brodin was pleased with the robe, and he left the shop. Before he climbed on his donkey to ride home, the shopkeeper and the shop-assistant ran out.

"You didn't pay for the robe!" said the shopkeeper.
"But I gave you the trousers in exchange for the robe, didn't I?" replied Brodin.
"Yes, but you didn't pay for the trousers, either!" said the shopkeeper.
"But I didn't buy the trousers," replied Brodin. "I am not so stupid as to pay for something which I never bought."