Definition of PR

I can't remember where I got this definition of PR from, but it made me smile and got it's point across quite uniquely:

You're at a party.
You see a beautiful woman. You go over to her and say “I’m brilliant in bed. Do you fancy spending the night with me?” - That’s advertising.
You see another beautiful woman, and send your friend over to her. He says “My friend is brilliant in bed. Do you fancy spending the night with him?” - That’s marketing.
Then a third woman approaches you. She says “I hear you’re brilliant in bed. Do you fancy spending the night with me?”. - That’s PR.