236 The Big Bang Theory The Clean Room Infiltration 08 11 2014-12-11 Comedy / Romance Jim Parsons - Sheldon Cooper / Johnny Galecki - Leonard Hofstadter / Kaley Cuoco - Penny / Kunal Nayyar - Rajesh Koothrappali / Simon Helberg - Howard Wolowitz / Melissa Rauch - Bernadette Rostenkowski / Mayim Bialik - Amy Farrah Fowler / Laura Spencer - Emily Sweeney / Sara Gilbert - Leslie Winkle / Kevin Sussman - Stuart Bloom / John Ross Bowie - Barry Kripke / Carol Ann Susi - Debbie Wolowitz Leonard and Howard turn to Raj for help in dealing with a work emergency when they nearly come to blows after blaming each other for a potential disaster at the university. Amy throws an authentic Victorian Christmas party, while Sheldon seeks revenge on her for making him celebrate the holidays.