S01 E08 — The Grasshopper Experiment
On a blind date, Koothrappali discovers that he can talk to the opposite sex after a few drinks, but his date takes an interest in Sheldon.

S01 E09 — The Cooper-Hofstadter Polarization
Penny tries to mediate when Sheldon and Leonard disagree on whether to present their joint findings at a physics conference.

S01 E10 — The Loobenfeld Decay
Leonard and Sheldon try to avoid seeing Penny perform after hearing her sing, but the elaborate lie Sheldon tells leads to an unexpected result.

S01 E11 — The Pancake Batter Anomaly
Leonard and the boys avoid Sheldon when he gets sick, leaving Penny to nurse him back to health.

S01 E12 — The Jerusalem Duality
Sheldon and Leonard look for a way to derail a 15-year-old physics prodigy's research.

S01 E13 — The Bat Jar Conjecture
When Sheldon tries to prove his mental superiority as they train for the Physics Bowl, the guys kick him off the team and bring his nemesis (Sara Gilbert) aboard.

S12 E23 — The Change Constant
Sheldon and Amy await big news.

S12 E24 — The Stockholm Syndrome
Bernadette and Wolowitz leave their kids for the first time; Penny and Leonard try to keep a secret; Sheldon and Amy stick together; Koothrappali makes a new friend; the gang travels together into an uncharted future.

S01 E01 — Pilot
Leonard is happy to meet new neighbor Penny, but his roommate thinks he is chasing an impossible dream.

S01 E02 — The Big Bran Hypothesis
Leonard volunteers to sign for a package, hoping to make a good impression on Penny.

S01 E03 — The Fuzzy Boots Corollary
Unhappy to learn that Penny is seeing someone, Leonard summons the courage to ask another woman on a date.

S01 E04 — The Luminous Fish Effect
Getting fired gives Sheldon the opportunity to explore life beyond physics, but when he spends his time weaving ponchos and acting like a shut-in, Leonard calls Sheldon's mother for assistance.

S01 E05 — The Hamburger Postulate
Leonard, realizing his pursuit of Penny is fruitless, has an unexpected encounter with a fellow scientist (Sara Gilbert).

S01 E07 — The Dumpling Paradox
Penny sleeps on Leonard and Sheldon's couch when Wolowitz seduces her friend and takes over her apartment; in need of a fourth member, the guys ask Penny to join their "Halo" team.

S01 E08 — The Grasshopper Experiment
On a blind date, Koothrappali discovers that he can talk to the opposite sex after a few drinks, but his date takes an interest in Sheldon.

S01 E09 — The Cooper-Hofstadter Polarization
Penny tries to mediate when Sheldon and Leonard disagree on whether to present their joint findings at a physics conference.

S01 E10 — The Loobenfeld Decay
Leonard and Sheldon try to avoid seeing Penny perform after hearing her sing, but the elaborate lie Sheldon tells leads to an unexpected result.

S01 E11 — The Pancake Batter Anomaly
Leonard and the boys avoid Sheldon when he gets sick, leaving Penny to nurse him back to health.

S02 E05 — James Norton / The Streets
An ensemble of British actors and comedians performs in a series of sketches alongside celebrity guest hosts and musical acts.

S12 E23 — The Change Constant
Sheldon and Amy await big news.

S12 E24 — The Stockholm Syndrome
Bernadette and Wolowitz leave their kids for the first time; Penny and Leonard try to keep a secret; Sheldon and Amy stick together; Koothrappali makes a new friend; the gang travels together into an uncharted future.

S01 E01 — Pilot
Leonard is happy to meet new neighbor Penny, but his roommate thinks he is chasing an impossible dream.

S01 E02 — The Big Bran Hypothesis
Leonard volunteers to sign for a package, hoping to make a good impression on Penny.

S01 E03 — The Fuzzy Boots Corollary
Unhappy to learn that Penny is seeing someone, Leonard summons the courage to ask another woman on a date.

S01 E04 — The Luminous Fish Effect
Getting fired gives Sheldon the opportunity to explore life beyond physics, but when he spends his time weaving ponchos and acting like a shut-in, Leonard calls Sheldon's mother for assistance.

S01 E05 — The Hamburger Postulate
Leonard, realizing his pursuit of Penny is fruitless, has an unexpected encounter with a fellow scientist (Sara Gilbert).

S01 E07 — The Dumpling Paradox
Penny sleeps on Leonard and Sheldon's couch when Wolowitz seduces her friend and takes over her apartment; in need of a fourth member, the guys ask Penny to join their "Halo" team.

S01 E08 — The Grasshopper Experiment
On a blind date, Koothrappali discovers that he can talk to the opposite sex after a few drinks, but his date takes an interest in Sheldon.

S01 E09 — The Cooper-Hofstadter Polarization
Penny tries to mediate when Sheldon and Leonard disagree on whether to present their joint findings at a physics conference.

S01 E10 — The Loobenfeld Decay
Leonard and Sheldon try to avoid seeing Penny perform after hearing her sing, but the elaborate lie Sheldon tells leads to an unexpected result.

S01 E11 — The Pancake Batter Anomaly
Leonard and the boys avoid Sheldon when he gets sick, leaving Penny to nurse him back to health.

S01 E12 — The Jerusalem Duality
Sheldon and Leonard look for a way to derail a 15-year-old physics prodigy's research.

S01 E13 — The Bat Jar Conjecture
When Sheldon tries to prove his mental superiority as they train for the Physics Bowl, the guys kick him off the team and bring his nemesis (Sara Gilbert) aboard.

S03 E19 — Road Worthy
Brent helps Lacey buy a new car; Karen and Davis try to break the idea of cops in donut shops.

S04 E01 — Hair Comes the Judge
Karen is upset when Emma cuts Brent's hair; Hank promises to stain Lacey's deck.

S04 E02 — Dog River Dave
When a morning radio DJ impersonates Brent on his show, he goes out of his way to prove it's not him; Lacey is upset with her delivery service.

S04 E03 — Two Degrees or Separation
Oscar and Emma argue over the room temperature; Karen makes Lacey regret disobeying a local yield sign.

S04 E04 — Just Brent and His Shadow
Brent and Lacey mentor high school students; Emma decides to be nicer to Oscar.

S04 E05 — Demolition
Brent helps Hank tear down a barn; Emma receives multiple manicures; David hires Wanda to snap pictures of him working.

S04 E13 — The One With Rachel's Crush
Chandler has a hard time handling Kathy's new role in a play, in which she pretends to have sex with a handsome man.

S04 E14 — The One With Joey's Dirty Day
A visit to a strip joint fails to cheer up Chandler; Rachel gets Ross to go to an opera; Charlton Heston finds Joey in a compromising position during a movie shoot.

S04 E24 — The One With Ross' Wedding
Rachel frantically tries to get to London to tell Ross that she loves him before he marries Emily; Ross' parents argue with Emily's parents, Steven and Andrea Waltham.

S05 E01 — The One After Ross Says Rachel
Ross is distraught over the wedding; Emily punches Ross and flees from the reception; Monica and Chandler try to control their passions.

S05 E02 — The One With All the Kissing
Monica and Chandler are caught in a passionate embrace but try to prove it was innocent: Ross' wife won't speak to him; Phoebe feels neglected; Rachel appoints Monica as her advisor in romance.

S04 E15 — The One With All the Rugby
Chandler runs into Janice, now divorced, and finds her more irritating than ever; Ross plays rugby to impress Emily; Monica tries to figure out what a mysterious electrical switch in her new apartment does.

S04 E16 — The One With the Fake Party
Rachel throws Emily a phony going-away party so she can see Joshua outside of work, and pregnant Phoebe craves meat.

S04 E17 — The One With the Free Porn
Ross tells Emily (Helen Baxendale) how he feels about her; Chandler and Joey suddenly receive a free adult TV channel in their apartment; Phoebe gets some surprising news about her pregnancy.