Bazinga - Featured in these episodes:

• Season 2, Episode 23 - The Monopolar Expedition

  This episode features the first mention of Bazinga. Sheldon first uses it when he tricks Leonard into believing there was something wrong with his equations. Sheldon then pulls another of his "classic pranks" on Leonard by telling him that Penny secretly wants Leonard in her life in a "very intimate and carnal fashion". Finally, in the Arctic, Sheldon tricks Leonard into believing he forget to bring the flash-frozen brown rice.

• Season 3, Episode 3 - The Gothowitz Deviation

  Sheldon says Bazinga three times in this episode. First, Sheldon says it after telling Howard he's always wanted to go to a goth nightclub. Secondly, Sheldon says the Bazinga was implied when he suggested that with positive reinforcement he could have Penny "jumping out of a pool, balancing a beach ball on her nose".  Finally, when Leonard wonders what Penny has been talking about on the phone for such a long time, Sheldon says waitressing at the Cheescake Factory is obviously a "complex socioeconomic activity that requires a great deal of analysis and planning", followed by a Bazinga.

• Season 3, Episode 4 - The Pirate Solution

  Sheldon says Bazinga after another one of his classic pranks when he tricks Raj into believing he would to interview for a job working with Sheldon.

• Season 3, Episode 10 - The Gorilla Experiment

  After telling Howard that his shoes are delightful and asking where he got them, Sheldon says "Bazinga. I don't care."

• Season 3, Episode 14 - The Einstein Approximation

  Sheldon says Bazinga multiple times as he tries to escape from Leonard in a ball pit.

• Season 3, Episode 18 - The Pants Alternative

  While under the influence of alcohol as he gives his acceptance speech, Sheldon tells a science joke: "Why did the chicken cross the Mobius strip? To get to the same side, Bazinga!"

• Season 3, Episode 20 - The Spaghetti Catalyst

  When Penny asks Sheldon how he's been, he tells her "Well, my existence is a continuum, so I've been what I am at each point in the implied time period". After Penny asks him if he's just "coitusing" with her, Sheldon says Bazinga.

• Season 3, Episode 21 - The Plimpton Stimulation

  When the guys are surprised to hear Sheldon will be having a female companion stay in his bedroom, they wonder whether he's kiding them. Sheldon tells Howard "A, I rarely kid. And B, when I do kid, you will know it by my use of the word Bazinga". When Howard asks if the two of them will be sleeping in the same bed, Sheldon tells him "Yes. Bazinga."

• Season 3, Episode 23 - The Lunar Excitation

  As the guys get ready to perform a laser experiment on the roof of the apartment, Sheldon tells Howard that he regrets not bringing an umbrella as, with skin as fair as his, moon burn is a real possibility. When Howard asks him if that's "a Bazinga", Sheldon says it's "one of my best, don't you think?"

• Season 4, Episode 2 - The Cruciferous Vegetable Amplification

  After Leonard turned Sheldon's virtual presence device off as he rode to work, Sheldon remotely turned the device back on and said "Bazinga", causing Leonard to swerve into traffic.

• Season 4, Episode 5 - The Desperation Emanation

  After Sheldon and Amy webcam with her mother and deceive her into thinking they are in a sexual relationship, Sheldon tells Amy "I find myself wondering if we should actually engage in coitus at least one time in our relationship. Bazinga!"

• Season 5, Episode 7 - The Good Guy Fluctuation

  After finally getting his own back on Leonard with a prank involving him jumping out of a couch cushion dressed as a zombie, Sheldon exclaims "Bazinga, punk. Now we're even."

• Season 5, Episode 22 - The Stag Convergence

  During his toast to Howard on his stag night, Sheldon first says "Okay, kidding aside, Howard, you are a good friend. And I wish you nothing but happiness. Bazinga, I don't!". After Leonard chides Sheldon, he says "Double-bazinga, I do!". Later, when Raj mentions that Howard lost his virginity to his cousin and Howard points out it was his second cousin, Sheldon says she was also "the first woman [he] ever disappointed sexually. Ba-da-zinga!"

• Season 8, Episode 3 - The First Pitch Insufficiency

  When Sheldon tells Amy that Leonard and Penny are "just jealous because they'll never have a relationship as good as ours", Penny says "Isn't this when he says 'bazooka' or something?"

• Season 8, Episode 15 - The Comic Book Store Regeneration

  As Sheldon listens to Barry thank Amy for her help on a paper he wrote, Sheldon suggests Barry e-mail it to him at "[email protected]"

  "Sheldon: Why .biz? Because I just gave you the business. And also bazinga.com was taken."

• Season 9, Episode 11 - The Opening Night Excitation

  When Sheldon describes one of his ideas for Amy's birthday present - an all-expense-paid trip to the "Wisconsin Sheep and Wool Festival" - Penny pauses and says, "Sorry, I was waiting for the Bazinga."

• Season 12, Episode 4 - The Tam Turbulence

  When Sheldon imagined how his life would have been different if Tam had moved to California with him, we saw Tam chasing Sheldon in the ballpit as he said "Bazinga!" as Leonard did in "The Einstein Approximation".