DOBBY: Dobby has heard of your greatness, sir, but never has he been asked to sit down by a wizard, like an equal.
HARRY POTTER: You can't have met many decent wizards then.
DOBBY: No, I haven't.
Poor Dobby. He's a house-elf, which means that he's basically a magical slave. Dobby's totally shocked by the fact that Harry would talk to him with any kind of respect. But Harry didn't grow up in the magical world so he doesn't have all the class baggage that someone like Draco or even Ron does. Dobby is just a weird little creature to him. Harry doesn't know that house-elves aren't unequal.
GILDEROY LOCKHART: Nice big smile, Harry. Together, you and I rate the front page.
Sure, Gilderoy Lockhart is famous, but Harry Potter is probably even more famous. It makes sense that Lockhart would be drawn to the Boy Who Lived—it increases his own star power to be teaching this celebrity pupil. And, unlike Harry, Lockhart needs love and adoration from society.
LUCIUS MALFOY: Mr. Potter! Lucius Malfoy. We meet at last. Forgive me, your scar is legend. As, of course, is the wizard who gave it to you.
HARRY POTTER: Voldemort killed my parents. He was nothing more than a murderer.
LUCIUS MALFOY: And you must be Miss Granger. Yes, Draco's told me all about you. And your parents. Muggles, aren't they? Let me see. Red hair...vacant expressions...tatty second hand book...you must be the Weasleys.
In the course of about two minutes Lucius Malfoy manages to insult just about every major character in the Harry Potter movies. He openly admires Voldemort, he looks down on Muggles, and mocks the Weasleys' financial situation. Lucius clearly thinks he's above his company. Now we know where Draco gets it from.
RON WEASLEY: Those are Nimbus Two Thousand Ones. How did you get those?
MARCUS FLINT: A gift from Draco's father.
DRACO MALFOY: You see, Weasley, unlike some, my father can afford the best.
HERMIONE GRANGER: At least no one on the Gryffindor team had to buy their way in. They got in on pure talent.
DRACO MALFOY: No one asked your opinion, you filthy little Mudblood.
Okay, so not only is Draco pointing out that he's an upper class wizard who's dad is way richer than anyone else in the vicinity, he's also no stranger to throwing out nasty slurs. Draco calls Hermione a Mudblood to let her know that he thinks she's beneath him in magical purity as well. Oh, it's on.
HERMIONE GRANGER: He called me a Mudblood.
RUBEUS HAGRID: He did not.
HARRY POTTER: What's a Mudblood?
HERMIONE GRANGER: It means "dirty blood." Mudblood's a foul name for someone who's Muggle-born. Someone with non-magic parents. Someone like me. It's not a term one usually hears in civilized conversation.
And now we get an explanation of what exactly a Mudblood is. It's basically the wizard version of every nasty not-fit-to-print name you can think to call someone. And it's all about who has the most wizards in their family and the "purest" magical blood. It's all pretty gross if you ask us.
GILDEROY LOCKHART: Harry, Harry, Harry. Can you possibly imagine a better way to serve detention than by helping me to answer my fan mail?
HARRY POTTER: Not really.
GILDEROY LOCKHART: Fame is a fickle friend, Harry. Celebrity is as celebrity does. Remember that.
We can think of several better ways of spending detention than helping Lockhart. Some of them involve flesh-eating slugs. But Lockhart tries to give Harry advice about fame. Why do we suspect he wouldn't take his own advice?
PROFESSOR MCGONAGALL: Salazar Slytherin wished to be more selective about the students admitted to Hogwarts. He believed magical learning should be kept within all-magic families. In other words, pure-bloods. Unable to sway the others, he decided to leave the school. Now, according to legend Slytherin had built a hidden chamber in this castle known as the Chamber of Secrets. Though, shortly before departing, he sealed it until that time when his own true Heir returned to the school. The Heir alone would be able to open the Chamber and unleash the horror within, and by so doing purge the school of all those who in Slytherin's view, were unworthy to study magic. Muggle-borns.
This is Salazar Slytherin's whole philosophy on magical class and purity right here. Why should Hogwarts teach students who aren't pure-blood? Shouldn't magical learning be ultra exclusive? Why should the magical gene pool be deluded with Muggles?
DOBBY: Dobby remembers how it was before Harry Potter triumphed over He-Who-Must-Not-Be-Named. We house-elves were treated like vermin, sir. Of course, Dobby is still treated like vermin.
It's good that house-elf living conditions improved a little after Voldemort was killed. A victory for the lower classes! But, wow, Dobby's family must be really awful.
DRACO MALFOY: You'd never know the Weasleys were pure-bloods, the way they behave. They're an embarrassment to the wizarding world. All of them.
Draco doesn't know he's talking to Ron Weasley (disguised as his friend, Goyle) right now. But, this pretty much reflects his thinking. The Weasleys are traitors to pure-blood wizards because they choose to fraternize with Muggles and, you know, not support genocidal maniacs like Voldemort. What weirdoes.
HARRY POTTER: Open it.
DOBBY: Master has given Dobby a sock.
LUCIUS MALFOY: What? I didn't give...
DOBBY: Master has presented Dobby with clothes. Dobby is free.
This is probably our favorite scene in the whole movie. Lucius is tricked into giving Dobby his freedom and he is not happy. The class structure has been upended. The master no longer has his servant. But, in Harry's eyes, justice has finally been restored.