Starlets like Paris Hilton, Lindsay Lohan and Emma Roberts partied it up in the Hollywood Hills to celebrate promoter pal Allison Melnick's birthday on Friday, and Princess P gave her bestie quite the toast -- click the video above to see what all the heiress had to say!

Paris is currently in NYC, and after that she'll be heading to Las Vegas for the Electric Daisy Carnival this weekend. She's quite the party hopper!