Episode Title:Percy's New Whistle.Episode Description:Percy brags to 'Arry and Bert that his whistle is louder than their horns, and begins showing off with it, but causes trouble for the others, and eventually himself when a giant snowball hits him. The Fat Controller then lectures Percy that whistles are to be used for emergency purposes only, and not for playing games. Percy then promises never to use his whistle for playing games again. And the next day, when Percy discovers a snow-slide blocking the line, as well as Thomas heading directly for it, Percy sounds his whistle, and Thomas stops just in time. Thomas thanks Percy for alerting him, and that night, the Fat Controller congratulates Percy for using his whistle correctly, calling him a really useful engine and a safe one, too.