Here's what he posted on his blog:
We decided to throw an impromptu house party on Saturday night - thanks Eric! - for no special occasion.
It wasn't anyone's birthday. We were just in town, we knew that a bunch of our friends were in town and since it's rare for so many of us to all be here at the same time, we thought it was the perfect opportunity for a party.
No expectations. No RSVPS.
And we honestly had the best time ever!
Some of our favoritest people in the world showed up, some you don't know and some you might - like Katy Perry, Mika, Josh Groban, Lady Gaga, Amanda Bynes, Emmy Rossum, Michelle Trachtenberg and Diane Warren.
