(Caution: some spoilers ahead)

"The Big Bang Theory's" milestone 200th episode "The Celebration Experimentation" airs this week and centers on a birthday celebration for Sheldon (Jim Parsons). But Sheldon, the persnickety pal that he is, isn't terribly keen on the party premise - largely because of scars from birthdays gone wrong as a kid. Like any good ride-or-die homies though, Amy (Mayim Bialik), Leonard (Johnny Galecki), Howard (Simon Helberg) and Raj (Kunal Nayyar) rally to make the day special, approaching Stuart (Kevin Sussman) to find a way to make the original Batman Adam West part of the day.

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It's a strange mix with the addition of guest stars Wil Wheaton, Sara Gilbert, John Ross Bowie and Christine Baranski and showrunner Steven Molaro's gave TVGuide.com some inside scoop on what you can expect from the festivities.

How hard was it to get Adam West to take part? There's a pretty robust and hilarious debate about who's the best Batman, too - how'd he take to that?

Steven Molaro: We'd been trying to get him for a while. We tried last season and came pretty close. We were super excited to get him this year; it's always tricky when actors are playing themselves. But he was incredibly nice and deeply funny. He's pretty comfortable [with 'best Batman' comparisons.]

Some fan sites have Sheldon's birth year as 1980, which would make him 36 this week. But how old is Sheldon really?

Molaro: That may be true. I don't know his exact age. It's possible it came up and over the course of 200 episodes I don't remember. I'm happy to keep it vaguely in his mid 30s.

There's so much going on, we don't get to see the unwrapping of presents! So wondering if you can clue us in to what Sheldon gets in terms of gifts?

Molaro: That's an amazing question. I stood there, looked at the presents, wondering 'What did they get him?' myself. We'll leave it as a happy mystery!

The 200th episode of "The Big Bang Theory" airs Thursday, Feb 25 on CBS.

Check out sneak peeks of The Celebration Experimentation" below!