Britney Spears appearing on the Britney episode of "Glee" is really happening -- and today, we got our first shot of her on set, thanks to Brit Brit herself!

Britney Spears Glee Episode
Spears just tweeted the above pic of her at McKinley High with her assistant Brett, looking cute in some glasses, a professional looking top and long extensions.

Brit adds "what's up GLEEKS? Having so much fun on set!! Can't wait for you guys to see the episode!" (See more photos from the "Glee" set!)

The highly anticipated second season of "Glee" starts up September 21.