Season 5, Episode 15 | February 2nd, 2012
After Sheldon keeps Leonard up all night with an natural disaster drill, Leonard decides that he needs a break from taking care of Sheldon. Hurt, Sheldon invokes clause two-oh-nine of their Roommate Agreement, which minimizes their interaction and 'legally' ends their friendship. After a while, Leonard starts to feel bad for Sheldon because he has no idea how to take care of himself on his own. Sheldon proposes they celebrate 'Leonard's Day' once a year to celebrate all of Leonard's contributions to his life, and Leonard then agrees to reinstate the Roommate Agreement. Meanwhile, Wolowitz is preparing to go on a flight to the International Space Station, and he notices that all of his crew mates have cool astronaut names. He enlists Koothrappali to help him subliminally plant the name 'Rocket Man' into his crew mates' minds, but their plan fails and his crew code name becomes Fruit Loops.