Sheldon and Penny's relationship is one of the key attractions of CBS's popular comedy "The Big Bang Theory." The introduction of Amy in Sheldon's life has not diminished the importance of Penny in Sheldon's life. It looks like in the upcoming episode Amy will admit to being jealous of Penny and Sheldon's friendship. The synopsis of the episode suggests an "unexpected friction between Penny, Amy and Bernadette" thanks to Sheldon's attempt to be spontaneous.

"The Big Bang Theory" Season 7 Episode 21 is titled "The Anything Can Happen Thursday Recurrence." According to CBS' brief synopsis, Leonard tries to help Sheldon free his mind by reinstating "Anything can happen Thursday."

In the previous episode, Sheldon broke-up with the string theory, after realising that he has nothing to show despite working on the theory for years. According to the spoilers leaked online, Sheldon continues to complain about his professional failures in "The Anything Can Happen Thursday Recurrence." Penny will be seen complaining about her horrible movie, 'Apeist-2', as well. Amy and Bernadette will be fed-up with Sheldon and Penny's incessant complaining. The spoilers suggest that they will lie to get away from Penny and Sheldon.

Later, Penny and Sheldon will find Amy and Bernadette having dinner, together. The two girls will admit that they are tired of Sheldon and Penny's complaining. Leonard will join them for dinner, while Penny and Sheldon will leave to have dinner at some other place. According to the spoilers, Penny will later take Sheldon to a psychic.

Amy will feel bad about lying to her boyfriend and will also admit that she is jealous of Penny and Sheldon's friendship, according to the spoilers.

Official Synopsis of "The Big Bang Theory" Season 7 Episode 21 "The Anything Can Happen Thursday Recurrence": "When Sheldon tries to be spontaneous, it leads to unexpected friction between Penny, Amy and Bernadette. Meanwhile, Raj seeks Howard's help in preparing for a date with Emily."

This episode, directed by Mark Cendrowski, is scheduled to air on April 24, 2014. Steven Molaro, Eric Kaplan and Adam Faberman have written the story, while Jim Reynolds, Steve Holland and Tara Hernandez have done the tele-play.