An interplay among Wolowitz, Sheldon, and Leonard is set to take place in "Big Bang Theory" season 9 episode 18. Also, Sheldon's odd secret will be unveiled in the episode.

"Big Bang Theory" season 9 episode 18 is entitled "The Application Deterioration." According to Spoilers Guide, the episode will see Wolowitz having second thoughts about engaging into a legal partnership with Sheldon and Leonard. The trio run into problems when they attempt to file for a patent for their infinite persistence gyroscrope.

"The Application Deterioration" is also set to see Penny, Bernadette, and Amy give advice Koothrappali about dating. He asks the three as to whom he should entertain between Emily and Claire. Also, Emily also reaches out to him after they split up.

In other news, "Big Bang Theory" season 9 will also reveal some vital information about Sheldon, who is played by Jim Parson, according to series executive producer Steve Molaro.

In his interview with Entertainment Weekly, Molaro said that Sheldon would share something strange about himself to his girlfriend Amy, who is played by Mayim Bialik. According to Molaro, that secret was something he had been hiding for a long time that nobody knew. Since bestfriends share their secrets at times, it is also unknown whether Sheldon shares his secret to his best buddy Leonard, who is played by Johnny Galecki.

"Big Bang Theory" centers on bestfriends Leonard and Sheldon, who are physicist at the California Institute of Technology. While they are highly knowledgeable in science, topics involving the opposite gender challenges them.

"Big Bang Theory" season 9 episode 18, "The Application Deterioration," is set to air on Mar. 10.