Jim Parsons as Sheldon Cooper in 'The Big Bang Theory'
Jim Parsons as Sheldon Cooper in 'The Big Bang Theory'Facebook/ The Big Bang Theory

Jim Parsons, the star of the People's Choice Award winning show "The Big Bang Theory", will turn 42 on 24 March, Tuesday. Parsons is most famous for his role in the CBS sitcom as Sheldon Cooper, a theoretical physicist.

The Emmy and Golden Globe-winning actor is doing press runs for his upcoming animated movie "Home", and while Parsons may be too busy to celebrate his birthday, fans can do so by reliving his character Sheldon's best quotes. Being a former child genius, with utter lack of social skills and an inability to understand irony and sarcasm, Sheldon usually gets to say the best lines in "The Big Bang Theory".

Here are some of the best quotes of Sheldon Cooper from all the eight seasons of "The Big Bang Theory".

The Big Bran Hypothesis (Season 1 Episode 2)

Leonard and Sheldon are unsuccessfully trying to carry a heavy object, at which point Sheldon says, "Ah, gravity—thou art a heartless bi**h."

The Lizard-Spock Expansion (Season 2 Episode 8)

Sheldon explains his variation of the classic game rock-paper-scissors.
Scissors cuts paper, paper covers rock, rock crushes lizard, lizard poisons Spock, Spock smashes scissors, scissors decapitates lizard, lizard eats paper, paper disproves Spock, Spock vaporises rock, and as it always has, rock crushes scissors.

The Jiminy Conjecture (Season 3 Episode 2)

Raj: I don't like bugs, okay? They freak me out.
Interesting. You're afraid of insects and women. Ladybugs must render you catatonic.

The Boyfriend Complexity (Season 4, Episode 9)

Leonard: You'll never guess what just happened.
Sheldon: You went out in the hallway, stumbled into an inter-dimensional portal, which brought you 5,000 years into the future, where you took advantage of the advanced technology to build a time machine, and now you're back, to bring us all with you to the year 7010, where we are transported to work at the think-a-torium by telepathically controlled flying dolphins?
Leonard: No. Penny kissed me.
Sheldon: Who would ever guess that?

The Justice League Recombination (Season 4 Episode 11)

Zack: You know, I saw this great thing on the Discovery Channel. Turns out if you kill a starfish it'll just come back to life.
Sheldon: Was the starfish wearing boxer shorts? Because you might have been watching Nickelodeon.

The Russian Rocket Reaction (Season 5 Episode 5)

Howard: Someone has to go up with the telescope as a payload specialist and guess who that someone is.
Sheldon: Mohammed Lee.
Howard: Who's Mohammed Lee?
Sheldon: Mohammed is the most common first name in the world. Lee, the most common surname. As I didn't know the answer, I thought it gave me the mathematical edge.

The Decoupling Fluctuation (Season 6 Episode 2)

Sheldon: If you're going to replace Wolowitz, I need to know a little bit more about you.
All right.
Wolowitz went to MIT. What's your educational background?
I went to art school.
Equally ridiculous. Let's go.

The Hofstadter Insufficiency (Season 7 Episode 1)

Sheldon: A while ago YouTube changed from a star-based rating system to a thumbs-up rating system. I pretend I'm okay with this, but I'm not.

The Focus Attenuation (Season 8 Episode 5)

Sheldon (to Leonard): I know the real reason you never made progress with that idea. You thought of it on September 22nd 2007. Two days later, Penny moved in and so much blood rushed to your genitals, your brain became a ghost town.

The Expedition Approximation (Season 8 Episode 6)

Raj: Sheldon, you busy?
Sheldon: I'm always busy. This mind is capable of advanced multi-tasking. Currently, I'm attempting to solve the Penrose Conjecture, I'm composing my Nobel acceptance speech for when I've solved the Penrose Conjecture, and I'm wondering how mermaids have babies.