It's been 45 days since Penny and Leonard said goodbye to Sheldon at the train station and when we first see the loveable nerd, it's clear time has not been kind to him. His hair’s a mess, he’s been robbed of all his belongings, and he's stranded at an Arizona train station in only his tighty-whities. In his moment of weakness, who does he call for help? Trusted roommate Leonard, who reluctantly sets off to pick up his friend.

He’s less than enthused to find out that Amy has come along for the ride and puzzled when she seems upset with him. She didn’t take kindly to him leaving her for over a month, without even saying goodbye. On the long ride home from Arizona, Amy questions his reasoning for calling Leonard instead of her. Sheldon insists that she cover her ears so he can speak privately to Leonard.

“As soon as we get home, I want to have coitus with Amy.” Sheldon confesses.

But don’t get too excited, in the laugh-out-loud moment of the night, he quickly follows it up with “Okay good, she can’t hear.”

Once Sheldon’s sure Amy isn’t listening, he explains that he just didn’t want her to know he couldn’t make it on his own. Amy later sweetly assures him that his imperfections only make her like him more, which of course he only finds insulting.

And so Sheldon returns home, ready to embrace change. At least until he sees Penny’s new pixie cut which prompts him to say what many viewers might be thinking “Your hair is different. You changed your hair. I can’t take this, I’m out.”

He is however, welcome to a change in careers. After some hesitation Sheldon accepts a position as a professor upon discovering that it would allow him to study dark matter. Unfortunately his bad reputation precedes him and no one signs up for his class besides Howard. This leads to a battle of the brains between the two friends as well as Sheldon acknowledging he is insecure about anyone he fears may be as smart as he is.

Meanwhile, a haircut isn’t the only change Penny has embraced. Her days at The Cheesecake Factory are done and with the help of Bernadette, she scores a job as a pharmaceutical rep. Friction develops between the two when Bernadette believes Penny isn’t doing enough to prepare for the new gig, giving Amy a chance to play the middle man.

Amy relishes in playing the part of the high school mean girl, but luckily, tension between the trio is resolved by episode's end.

The Big Bang Theory airs Monday nights on CBS.