Sheldon is trying to persuade Penny to stop crying.
谢尔登劝说彭妮不要哭泣。
Sheldon: Why are you crying?
谢尔登:你为什么哭?
Penny: Because I' m stupid!
彭妮:因为我太笨了!
Sheldon: That's no reason to cry. One cries because one is sad. For example, I cry because others are stupid, and that makes me sad.
谢尔登:那也没有理由哭啊,人因为伤心才哭。比如说我哭是因为其他人都太蠢让我感到悲伤。