This monologue is a demonstration of the power of advertising in general, and in particular it is a testament to the importance of name and product recognition in drawing customers.
After reviewing the book in which he records names and important information about his friends (this monologue is apparently from someone who is not tech-savvy enough to have a smartphone with a digital database of his friends) and finding the list short, the speaker decides he needs to do something to make himself more attractive to others. Based on his knowledge of Justin Timberlake's reputation and social influence, he purchases and uses cologne marketed in association with Timberlake's name. The speaker credits this with his newfound popularity and numerous new friends.
The speaker realizes his physical appearance is not as muscular and manly as he wishes. Based on the advertising he has probably seen on television of athletes wearing Calvin Klein underwear, he purchases and begins wearing the same products himself. With just this change in underwear, he now has a "buff" body that is attracting all the sexual attention he wants.
Having seen Marlboro ads showing strong men mastering heavy activities in rugged settings, the speaker begins smoking Marlboro cigarettes himself. He now feels himself projecting a stronger image to those observing him.