Trivia: The painting with Seth and James' name were painted by James Franco. He also helped paint Freaks and Geeks.
Trivia: There was a persistent rumor that Emma Watson stormed off set after seeing one of the scenes they were shooting. (The scene with cannibalism and the Channing Tatum-gimp.) Seth Rogen later clarified that Watson simply wasn't comfortable shooting the scene since it was very weird, improv-heavy and different from the script, so she politely asked not to shoot it. She came back to set the very next day to say good-bye to everyone, had a good time making the movie otherwise, and even promoted it.
Answer: He is explaining that she would not eat a whole seventh of the food, referring to how many survivors are in the house. As she is so small, she would only eat half of what would be her share of the food if they divide it equally.