The guys get back from the North Pole and tell Sheldon they altered his research in an effort to put him in a better mood for the duration of the trip. Sheldon is humiliated because he already notified his colleagues at the university of his successful expedition. Devastated, he resigns from the university and runs back home to Texas and his mother (played by Laurie Metcalf). The guys go after him in an effort to convince him to come back with them.
Penny is so excited to see Leonard back from the trip that she immediately drags him into her apartment, kissing him incessantly. Both soon realize that being "friends with benefits" is not necessarily a natural fit for them.
