The tailor gave him the trousers, and Nasruddin tried them on.
"They're not quite right," he said, giving them back to the tailor. "I'd like to try a jacket now, please."
Nasruddin liked the jacket very much. "I'll take it!" he said, and then he began to walk out the door.
"But wait!" shouted the tailor. "You haven't paid!"
"I exchanged the trousers for the jacket," Nasruddin explained.
"But you didn't pay for the trousers!"
"Of course not!" said Nasruddin. "I didn't want the trousers!"
Inspired by: Classic Tales of Mulla Nasreddin retold by Houman Farzad, and translated by Diane Wilcox
Notes: This story is on p. 56 of the book.