On Purim there is a comprehensive breakdown of decorum in shul, the most blatant expression of which is the outbreak of noise-making whenever Haman's name is uttered during the Megillah reading. There are many more hi-tech ways of doing this than the wooden groggers and dried-peas in a sealed Coke-can of my childhood.
The Rama, Rabbi Moses Isserles (16th century), wrote that children have the custom of "drawing images of Haman on wood and stones, or writing the name Haman upon them, and then banging the two objects together in order to erase Haman. This accords with the verses, 'You must obliterate any mention of Amalek' (Deuteronomy 25: 19)."
Despite its childish origins, the practice's persistence is serious. Amalek launched the first unprovoked attack on the Jewish people. Haman, his descendant and the villain of the Purim story, tried to wipe out all the Jews of Persia. We may not forget that genocidal antisemitism still exists today and that we ignore it at our peril.