Leonard finds out that he and Sheldon were invited to a physics conference, but Sheldon had thrown away the letter. When he confronts Sheldon, Sheldon states that he does not want to be in a room of peopl, who are less smart than he and try to pander up to them. Leonard however, feels that this is an honor and wants to present it, though Sheldon "forbids" it.
Leonard tells Penny the problem, and she tries to help him by consoling Sheldon. But when she tells Sheldon that Leonard said Sheldon played a "minor" part in the research, Sheldon tells Leonard never to talk to him ever again.
When Leonard finishes presenting at the conference, it turns out that Sheldon was there all along. Sheldon tells Leonard that he presented wrongly, and that he's just doing this to impress people because he has an ego. Leonard yells at Sheldon, telling him that he's not the only one in the room who's smarter than everyone else. The two men fight in front of their colleagues, but they later make up.