Complex sentence: When teaching or transacting academic business during the day he displayed a shrewd, canny intelligence; however, at social gatherings, and much to the delight of his students, he was unceasingly outrageous and flippant.
Split into simpler sentences: When teaching or transacting academic business, he displayed a shrewd, canny intelligence. However, at social gatherings, and much to the delight of his students, he was unceasingly outrageous and flippant.