"The Cohabitation Experimentation" -- Pictured: Penny (Kaley Cuoco). When Amy's apartment floods, she proposes a "cohabitation experiment" with Sheldon. Also, Howard and Bernadette are upset when Koothrappali learns the gender of the baby before them, on THE BIG BANG THEORY, Monday, Oct. 10 (8:00-8:31 PM, ET/PT), on the CBS Television Network. Photo: Michael Yarish/Warner Bros. Entertainment Inc. ÃÂ© 2016 WBEI. All rights reserved.