Like other posters have said, I would find this type of behaviour simultaneously annoying and sad.
If it was a good friend, I'd pull them aside and gently tell them "You're a great person the way you are. You don't have to try to be someone you're not".
Unfortunately, as this is Samgirl's boss, not her friend, I don't think there's anything to be gained by talking to her about this. In fact, there's high chance she could go into denial and get really offended. Which would make things awkward at work.
I'd give polite, yet vague answers the things she says. Eg:
Her: "What did you think of my latest blog entry?!"
Samgirl: "Yeah, it was interesting."
Her: "You should only eat lunch with people who can help your career!"
Samgirl: "Hmm, thanks, I'll keep that in mind."
Her: "I have the latest iPhone Six!!!!"
Samgirl: "Oh, nice."