It's Britney, Gleeks!

Britney Spears became a hot cheerleader -- and way more -- on Tuesday's Glee.

In the hugely anticipated Britney episode, the pop queen was fantasy girl for McKinley High's Glee club singers, who hallucinate about her while under anesthesia at the dentist.

As ditzy Brittany (Heather Morris) sees herself in the "Me Against the Music" video with pal Santana (Naya Rivera), Spears, 28, steps in for a sexy chat.  Gasps Brittany: "You're really hot!" 

Next, the star talks pizza toppings (ranch dressing!) and dons a tight-fitting uniform in wheelchair-bound Artie's (Kevin McHale) steamy dream.

Watch Spears flirt and chat with the Glee kids in this clip (above) -- and tell Us: What'd you think of the episode?