Stephen Hawking made a triumphant virtual return to The Big Bang Theory in "The Extract Obliteration."

Sheldon, ever desperate to make certain friends, was ecstatic when he started playing Word with Friends with Hawking. Surprisingly, neither Sheldon nor his pals mentioned the unfortunate mathematical error made during their previous actual meeting.

Hasn't everyone who has played Word with Friends wondered at one time or another why their opponent has stopped playing? Or possess that one friend they either always beat or always lose to? Add in playing against an idol and we have Sheldon's hilarious Word with Friends adventure.

Sheldon's superiority complex of being close with Hawking and his willing Hawking to play provided laughs. The best part was when Sheldon tried in all seriousness to use a Jedi mind trick to get Hawking to participate.

In the end, I was a bit surprised that Sheldon threw the game. That may be the first time we have ever seen Sheldon let someone best him. It was especially poignant after he reprimanded Amy for helping him with a word. Can you think of any other instances? 

While Sheldon was busy playing - or not playing - games, Leonard was dealing with the aftermath of finding out Penny was taking a college class. Penny knows Leonard so well, doesn't she? Of course he loves her, so he's going to want to help.

Only that always - yes, always - ends in disaster for him and hurts their relationship. At least this time, when Leonard butted in, it ending up helping Penny. The breakfast in bed and shoemaker's elves story was quite cute and I thought it would cushion the blow a little more than it did. But Penny was strong in her conviction.

I cheered for Penny when she showed Leonard her B-. Good for her. And Penny's imitation of Leonard cracked me up. I hope Penny pulls that out again, it's sure to make me laugh every time.

Penny ended up not doing it all on her own, though. Kudos for recognizing the need for help, that's what friends are for. Though, from the sounds of it, Bernadette and Amy had to give A LOT of assistance. I hope if the school thing comes up again that Penny is learning and growing from her experience.

In the past, a fight like this would have put a big dent in Penny and Leonard's relationship. This time, they didn't talk for a couple days, but seem to still be going strong. They do belong together, Leonard just needs to learn some boundaries.

Odds and Ends

• Poor Bernadette using Mrs. Wolowitz's underwear as a towel. She really must convince Howard to move into their own place. 
• Did Raj learn his American accent from watching cowboy movies? It was bad. Very bad. Howard had a much better Indian accent.
• Hawking went from Wheels, to being called a baby, to Rolling Thunder. 
• Leonard and Sheldon's fight was the only part I didn't really care for. It's situations like that which make me question why they even live together. That takes me out of the humor (if there is any) of the exchange. Though, the chess clock did add a nice uniqueness to the situation.
• Amy: I feel like I'm in high school again.
  Bernadette: Yeah, doing the prom queen's homework, so she'll like us.
  Amy: I know. It's finally working. | permalink
• Professor Hawking: What do Sheldon Cooper and the black hole have in common? They both suck. | permalink

Carla Day is a staff writer for TV Fanatic. Follow her on Twitter and on Google+.