Well known is the custom to clamor each time Haman's name is read in the Megillah, but some also clamor in another place. The third last verse of the Megillah tells us King Ahasuerus imposed tax on the mainland and the islands. Many demonstrate their displeasure by clamoring when the word tax is pronounced! Malbim suggests that this seemingly superfluous detail was included to show Mordechai was successful as a leader, for taxes can only be collected from a thriving population.