Katy Perry threw a massive Halloween party on Saturday night.
The Roar singer seemed to be inspired by the 1878 Olivia Newton-John and John Travolta movie Grease as the event had a 1950s high school theme.
Pal Kate Hudson was dressed up as a wild girl with Orlando Bloom as a jock.
Perry wore a yellow beehive wig with a yellow top and matching tweed skirt suit.
At one point she wore glasses and held onto a ruler in a classroom
Also with Katy was Kate in a black crop top that showed off her toned tummy and a circle skirt with yellow checkers.
Her hair was pulled back with a bandanna and she seemed to have a motorcycle jacket on.
There was also a female pal with a pink poodle skirt on and a man dressed as a nerd with suspenders.
Her beau Orlando Bloom was dressed as a jock in a red jacket with a B on it and a whistle around his neck.
His hair was dyed blonde for a film role.
Also at the event were Cheerleaders with a H on their tops maybe for Hudson. Katy's real name is Katheryn Elizabeth Hudson.