Sheldon insisted to grow cultures because he thought it would be his fighting chance when he was lying comatose in a hospital and relying for inferior minds to cure him.
When Leonard didn't think so and wanted to go back to bed, Sheldon asked him to put a measuring cup in bathroom for measuring his fluid intake and output to make sure his kidneys are not shutting down.
Leonard thought it was really disgusting because he used that measuring cup for mixing pancake batter and questioned Sheldon why he didn't make a label for it since he has made a label for everything in the apartment. Sheldon showed Leonard he did it by letting Leonard see the label on the bottom of the cup.
Leonard realized that he misunderstood Sheldon and expressed his apology though it seemed he didn't really mean it.
comatose: deeply unconscious from serious injured on part of brain, deep sleep.
inferior: if you describe something is inferior, you think it is less important or not as good as something else.
accompany: to be with, to go with
culture: the activities help developing civilization of a country.
cure: to help recovering from a disease.
fluid: a liquid
intake: the amount of drink or food you have.
output: to produce
batter: if you describe someone is battered, you mean they are hit by the family members or their partners; the mixture of flour and eggs.