It's finally here! The highly anticipated Britney Spears episode of "Glee" airs tonight -- and John Stamos is joining in on the fun.
The actor tweeted a fun pic with Heather Morris on Tuesday, with the caption, "Not the real Britney Spears, but an incredible simulation."
Stamos plays a dentist who gives Santana (Naya Rivera) and Britney (Heather Morris) laughing gas to put them under, which sends the girls into a Britney Spears dreamland.
Watch Britney and Santana perform a perfect reenactment of "Me Against the Music."
Catch "Glee" Tuesday, Sept. 28 on FOX!
Take "Extra's" "Glee" quiz to find out if you're the ultimate fan.