"The Big Bang Theory" is nearing the end of its ninth season, but that doesn't mean that things are going to get boring any time soon. In fact, the upcoming episode will be anything but, as Sheldon (Jim Parsons) and Leonard (Johnny Galecki) find themselves in the middle of a bout.

Hollywood Hills has posted the official synopsis of episode 21, titled "The Viewing Party Combustion." It reads: "Everyone is going to have to choose sides when a small argument between Leonard and Sheldon erupts into a heated fight during a group get-together."

Fans have seen the two roommates fight in past episodes and those have always proven to be both entertaining and funny ones. This time, however, everyone else gets involved as well, which will make for an exciting installment.

Meanwhile, here is a recap of what happened in the previous episode, titled "The Big Bear Precipitation."

The gang broke off into two groups for the entire duration of the episode—Leonard, Penny (Kaley Cuoco), Sheldon and Amy (Mayim Bialik) went to the woods, while Howard (Simon Helberg), Bernadette (Melissa Rauch) and Raj (Kunal Nayyar) spent their time at the Wolowitz home.

After experiencing nature through virtual reality and being encouraged by Amy, Sheldon decided to join Leonard and Penny in their trip to a cabin in the woods. However, things didn't go according to plan as rain fell hard, ruining their scheduled hiking. They decided to stay indoors and play a drinking game, Never Have I Ever, instead. Through the course of the game, it was revealed that Sheldon had been arrested before—albeit in a typical hilarious Sheldon way—Leonard calls his genitals "Alvin and the Chipmunks" and Penny has cleaned the sink using Sheldon's toothbrush.

In the process, the existence of Leonard's secret bank account, which he has kept from Penny, is also revealed. The two then momentarily fight over it before Penny admitted to a secret of her own: She hates her job. However, she knows that in order to pay off her credit card debts, she needs to keep at it.

Meanwhile, Raj becomes a bit too intrusive with Howard and Bernadette's new baby, from buying them an ultrasound microphone to listen to their baby's heartbeat to bringing Bernadette a comically gigantic bear. They ask him to back off at first, but eventually make up with him and ask him back.

"The Big Bang Theory" season 9 episode 21 will air on Thursday, April 21 on CBS.