What is Red Nose Day, and why are celebrities wearing clown noses?

Red Nose Day is here! The only problem? No one really knows what it is.

Leading up to Thursday (May 21) night’s event, celebrities have been posing with red clown noses on their faces and joking around with each other in fun videos. But what exactly is Red Nose Day and why is every celebrity so excited for it? The show is the U.K.’s No. 1 television fundraising event and thanks to its creator, Richard Curtis, it’s coming to the U.S. According to NBC, the event was “built upon the foundation that mass media and celebrities can help raise money and increase awareness of poverty in order to save and change millions of lives.”

Still confused about some of the basics? Take a look below to find out everything you need to know before Red Nose Day begins.

Is it like a telethon?

Kind of: it’s a fundraising event and variety show all in one.

What actually happens during the event?

The three-hour show will be filled with both live and pre-taped content. Red Nose Day will feature sketches—watch out for Game of Thrones: The Musical—live musical performances and a variety of other comedy bits. The benefit will also air short appeals films that “shed light on those in need.

What is it raising money for?

According to NBC, the money raised during the event “will be used to fund programs that address the immediate needs of children and young people living in poverty in the U.S. and internationally in Africa, Asia and Latin America.”

How long has it been going on in the U.K.?

Red Nose Day has been taking place in the U.K. for 30 years. To date, it has raised over $1 billion in donations.

Is there a host?

Several, actually. Seth Meyers, David Duchovny and Jane Krakowski are set to host the event.

So which celebrities are involved?

Um, a bajillion of them, basically. Get ready for this lineup:

Julia Roberts
Will Ferrell
Jennifer Aniston
Reese Witherspoon
Jodie Foster
Jimmy Fallon
Neil Patrick Harris
Ed Sheeran
Josh Groban
Christian Slater
Al Roker
Andy Cohen
Kellan Lutz
Kermit the Frog
Julianne Moore
Jack Black
John Krasinski
Emily Blunt
Michelle Rodriguez
Gwyneth Paltrow
Adam Levine
Blake Shelton
Christina Aguilera
Pharrell Williams
Richard Gere
Jennifer Garner
Keith Urban
John Mellencamp
One Direction
Coldplay
Zac Efron
Helen Mirren
Robert Pattinson
Liam Neeson
Nick Cannon
Sienna Miller
Paul Rudd
Olivia Wilde
Eddie Redmayne
Benedict Cumberbatch
Sir Ian McKellen
Orlando Bloom
Leslie Mann
January Jones
Simon Cowell
Matt Lauer
Carson Daly
Nick Offerman
Elizabeth Banks
Chris Pine
Jeff Goldblum
Billy Eichner
Martin Short
Laura Linney
Anna Kendrick
Sean “P. Diddy” Combs
John Michael Higgins
Bill and Melinda Gates
Stephen Merchant
Naomi Campbell
Anna Camp
Jeanne Tripplehorn
Yvette Nicole Brown
Retta
Natalie Morales
Danny Pudi
Rob Huebel.
Matt LeBlanc
Hugh Bonneville
Dame Diana Rigg
Kyle MacLachlan
Rose Byrne
Elisabeth Moss
Hoda Kotb
Gilbert Gottfried
Cheryl Burke
Nicole Scherzinger
Jeff Dye
Saturday Night Live cast members Jay Pharaoh, Colin Jost and Michael Che
Game of Thrones cast members Kit Harington, Peter Dinklage, Iwan Rheon, Nikolaj Coster-Waldau, Emilia Clarke, Thomas Brodie-Sangster, Mark Addy, John Bradley, Rose Leslie, Alfie Allen and Charlotte Hope
Orange Is the New Black cast members Dascha Polanco, Samira Wiley, Yael Stone, Selenis Leyva, Lea DeLaria, Adrienne C. Moore and Jackie Cruz

When does it air?

Red Nose Day airs on Thursday, May 21 from 8 p.m. to 11 p.m. ET/PT on NBC.

Photo via Sleeping Walrus/Flickr (CC BY SA 2.0)