A fleeting glimpse of Spears on 'Glee'

Blinked and you missed her. Stretched, yawned, or glanced away - the same. The Waldo of "Glee" was of course Britney Spears.

There for just a beat, she had to tell Brittany (Heather Morris) that her dental-induced fantasy was just a fantasy, and nothing more. There was an exchange of pleasantries, and an affirmation that both had gargled ("Your breath smells sweet" "Yours too.") And nothing more.

What a strange, strange "Glee." But strange can be good too, and some of this was very good.

If you missed it, a quick rundown. Brittany and pal Santana (Naya Rivera) were put under by dentist Carl Howell (John Stamos) and underwent brief, florid and highly choreographed reboots of "I'm a Slave 4 U" and "Me Against the Music." A snake was involved, of course - a large Burmese python, uncredited. Who knew Brittany and Santana could dance and sing? "Gleeks" do now; they were terrific, and so were the productions. Brittany's fantasy then ended: Britney, the real Britney, said it was all just a fantasy.

Last night's all-Britney episode was not quite all Britney - it ended with a song by Paramore ("The Only Exception") but Spears, otherwise, was inescapable. The episode captured that once-potent, once-ubiquitous sound, and what that all meant: The mood, the sex, the hormones and even the snake - whatever that was a metaphor for was.

Who next? Taylor Swift? Justin Bieber? Wait for the third season.