It was the 200th episode of CBS' 'The Big Bang Theory' last night (February 25th 2016) and, as part of this milestone celebration, we got to experience Sheldon Cooper's first ever adult birthday party. It was an episode that really showed how far he's come as a human being.

Big Bang Theory cast'The Big Bang Theory' celebrates 200th episode with Sheldon's birthday

Sheldon (played by Jim Parsons) has changed a lot over the last nine years. Not only is he in a long-term relationship, but he's finally given Amy Farrah-Fowler the intimacy she's been waiting so long for and he's learnt a lot about proper social interaction. He's resolved long-held feuds (Wil Wheaton) and worn some epic T-shirts, but the 200th episode was just a little bit different.

He's never wanted a birthday party, ever since his sister promised him Batman was coming to their joint sixth birthday and he waited for hours in front of the house only to realise that it was all just a mean prank. But Amy insists that she wanted to give him a memorable time like he did for her (wink, wink), and so he allows her to plan a party as she likes. Indeed, it all ends up being very lovely; Sheldon even wears a suit, though he is a little startled at first and has to be coaxed out of his bathroom hiding place by a compassionate Penny. His best friends Leonard, Raj and Howard are, of course, present and have even managed to bring Adam West, the original Batman from TV, to join them. 

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Howard's partner Bernadette, the comic book store owner Stuart and Leonard's ex Leslie Winkle are also there, as well as Leonard's mother Beverly Hofstadter (pretty much the female version of Sheldon) and Star Trek's Wil Wheaton who confesses that he's become a fan of Sheldon's over the years. Many kind words and birthday wishes were exchanged, which pleased the immodest Sheldon no end. He even had a tender embrace with Penny, where he said, 'You know, I used to hate these hugs. Now they're just extremely irritating', a content smile on his face nonetheless.

The icing on the cake? Stephen Hawking joined them over Skype to sing 'Happy Birthday'!