What was the one thing the Grinch like least of all?

The one thing the Grinch liked least of all was Christmas. He despised the joy and cheer the holiday brought to the Whos in Whoville, which he found irritating and bothersome. His disdain for the festivities drove him to plot against Christmas, ultimately leading him to steal the holiday from the Whos. However, he later discovers the true spirit of Christmas, realizing it goes beyond material gifts and decorations.