The next episode of "The Big Bang Theory" will be the season 10 finale and with Amy (Mayim Bialik) gone, Sheldon's (Jim Parsons) former admirer, Dr. Ramona Nowitzki (Riki Lindhome), will return.

The promo trailer for the upcoming episode hints at a big surprise, which will leave viewers shocked and possibly end season 10 with a cliffhanger. In the trailer, Penny (Kaley Cuoco) is seen talking to Sheldon and explaining something that deals with who his as a person. It then ends with Bernadette (Melissa Rauch) being surprised by something Penny has said.

There are a couple of options for what the surprise may be, especially with the comeback of Sheldon's ex, Nowitzki. CarterMatt released a few possibilities, including a possible affair between Sheldon and Nowitzki. After years of not appearing on the show, there has to be a reason to why she comes back and coincidentally at a time when Amy is gone.

Another possibility would be Sheldon proposing to Amy, especially because it's a known fact that he already has an engagement ring picked out. With Amy across the country working at her summer job in Princeton, Sheldon has more time to really think about their relationship and future together. Also, seeing his former admirer may make him realize how much he loves Amy, which ultimately leads to Sheldon proposing to her.

The least likely option, but possibly happening, is that another one of the characters may be pregnant. Howard and Bernadette have just welcomed their daughter this season, so "The Big Bang Theory" writers may want another addition to the gang. If this were the case, who could the pregnant person be? Amy or Penny? If Amy were the one to join Bernadette in motherhood, viewers will get a kick out of seeing Sheldon as a father as this is something out of his character.

"The Big Bang Theory" season 10, episode 24 is scheduled to air on Thursday, May 11, at 8 p.m. EDT on the CBS TV Network.