The "Big Bang Theory" gang is taking a road trip to Vegas. Well, most of the gang anyway.

Sheldon (Jim Parsons) wasn’t invited after allowing his friends to all wait on him hand and foot during a bout with the flu — but never saying “thank you.”

“I’m upset because everyone is mad at me for no good reason,” he shares with Amy (Mayim Bialik) during a video chat at the top of this week’s episode, “The Empathy Optimization.”

“You know how when you are sick, you are allowed to be cranky and say whatever you want and other people’s feelings don't matter?  I had 101 (degree) fever. If that is not a time to verbally abuse my loved ones, when is?”

What Sheldon doesn’t realize is that the rest of his besties are fed up with his constant neediness and looking to get as far away from him as they can.

“I wish we could do more stuff without Sheldon,” Raj (Kunal Nayyar) tell Howard (Simon Helberg) and Leonard (Johnny Galecki) during a visit to the comic book store.

That is where the plan is hatched to rent a party bus and make a weekend getaway to “America’s urinal cake.”

Sheldon learns of the trip and complains to Amy.

“Everyone tries to take care of you and you are nothing but mean to them,” she explains, urging him to apologize for being an unappreciative jerk while he was sick.

And the apology tour begins.

One by one, he tries to right his wrongs.

“I accept your apology, but you upset a lot of people when you were sick,” Leonard tells him, issuing the challenge for Sheldon to apologize to every one of his friends if he wants to be included on the trip.

First up:  Howard and Bernadette. He underscores the gesture with an offer to play Brenda Lee’s “I’m Sorry” on the pan flute and passes out T-shirts that read: “Sheldon Cooper apologized to me.”

Next, Sheldon tracks down Penny in the shower. She agrees to accept his apology if he leaves.

By the time he is done apologizing, Sheldon has once again insulted Emily’s career as a dermatologist. She gets into a fight with Raj and vows not to attend the trip if Sheldon is present.

The gang — sans Sheldon — eventually end up on the bus, which is tricked out with black lights and stripper poles.

As Leonard attempts to toast to fun, Sheldon emerges from the bathroom along with Stuart (who also was not invited).

They both agree to leave, but Emily says she feels sorry for Sheldon, prompting the bus to stop and Leonard to invite his “pain in the ass” friend (and Stuart) to get back on board.

As the journey begins, Sheldon asks Emily if she is relieved to have worked through her disagreement with Raj.

“Not really,” she says as the camera pans to Raj, shirtless and dancing around the pole.

“The Big Bang Theory” airs Thursdays at 8:00 PM on CBS.