Because Leonard (Johnny Galecki) got offended when his wife Penny (Kaley Cuoco) told him that he lacks physical coordination, he and the gang will start taking up fencing lessons in the fifth episode of "The Big Bang Theory" season 9.

Based on the promo trailer for the episode titled "The Perspiration Implementation," Penny mocks Leonard's coordination skills, and even revealed that he once twisted his ankle playing scrabble. To prove that Penny is wrong, Leonard asked his friends Sheldon (Jim Parsons), Howard (Simon Helberg), and Raj (Kunal Nayyar) to join him in a fencing class.

But while the boys are honing their coordination skills, Sheldon will find it hard to work with their fencing teacher Barry Kripke (John Ross Bowie) after the latter revealed that he is starting to have some feelings for Sheldon's ex-girlfriend Amy (Mayim Bialik).

Yet despite Sheldon's issue with Barry, the boys still seem to have fun with their fencing lessons, particularly with the fact that the proper fencing term for striking an opponent with a use of a fencing sword is called "touch."

The episode will also deal with Stuart's (Kevin Sussman) problems at the comic book store. Apparently, his customers are mostly male, and he rarely has female clients. Because of this, Penny, Amy, and Bernadette (Melissa Rauch) will offer to help him in his dilemma.

The fifth episode of "The Big Bang Theory" season 9 will air on Monday, Oct. 19, on CBS.

Meanwhile, TV Line confirmed early this week that actress Laura Spencer, who portrays the role of Raj's girlfriend Emily, has been promoted as a series regular cast member.

A source told the entertainment website that Spencer will be considered as a fractional series regular for the season. It means that the actress will have to be on standby to be available for shooting anytime for "The Big Bang Theory" season 9.