The Maternal Combustion
Season 8, Episode 23 - Aired April 30, 2015

When Sheldon and Leonard receive an award for the paper they co-wrote together, their mothers pay a visit to Pasadena. Sparks fly between Mary Cooper and Beverly Hofstadter when they can't see eye to eye on religion or psychiatry. Meanwhile, Bernadette has had enough of feeling like a mother to three teenage boys, so Howard, Stuart and Raj are ordered to clean the kitchen.