One day Nasreddin 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 shirt which had the same price as the trousers. Nasreddin was pleased with the shirt, 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 shirt!” said the shopkeeper.
• “But I gave you the trousers in exchange for the shirt, didn’t I?” replied Nasreddin.
• “Yes, but you didn’t pay for the trousers, either!” said the shopkeeper.
• “But I didn’t buy the trousers,” replied Nasreddin. “I am not so stupid as to pay for something which I never bought.”