Hop Along (1927)

Part of Universal's series of one-reel Bluebird Comedies, this one stars Arthur Lake as a student who's confined to his dorm room to study on the night of a big costume party. When Professor Wise (George B. French) comes to check up on him, he finds Lake in a bathrobe, book in hand. As soon as the prof leaves, Lake rips off the robe to expose his Scots costume.