"Glee" featured its 500th song and dance performance in Thursday night's episode, with cast members Jayma Mays (Emma) and Matthew Morrison (Will) singing and dancing their hearts out in a Fred Astaire and Ginger Rogers-inspired performance of "You're All the World to Me."

"So excited for Glee tonight and our 500th performance!" tweeted star Lea Michele.

But Twitter is on fire about whether Michele's character Rachel is pregnant.

Last last week's episode of "Glee" ended with a cliffhanger featuring Rachel holding a positive pregnancy test.

When Rachel's pregnancy was confirmed in Thursday's episode, Twitter exploded.

"Rachel's prego. Sheeeiiit," tweeted Autumn Blakee.

"Glee" fan Marisa is concerned about who is the father of Rachel's baby.

"I'm going to cry if that 1 dollar man prostitude is the baby daddy of Rachel's baby," Marisa tweeted.

When the character of Santana confronts Rachel on this week's "Glee" episode, she breaks down.

The female cast of the show had a couple powerhouse dance performances, "Diamonds Are a Girl's Best Friend" from "Gentlemen Prefer Blondes" and the Madonna hit "Material Girls."

Twitter user Lester Nieves wrote that Thursday night's episode featuring the 500th performance of "Glee" was impossible to avoid on the social networking site.

"Thanks, #glee, for reminding me that I can't escape from your shitty madness by nursing my back pain while skulking in the depths of Twitter."

But Sarah R., won't give into the Twitter pressure. "I'll watch glee tomorrow," she tweeted. "It gets over too late and I have a quiz in Psychology tomorrow."