The movie was autobiographic on his years growing up so I'm sure everything came pretty natural for him. I'm also going to be the first person to post a second video because it was damn hard to choose between the two. Damn Isollde and her hard, drunk questions.
If you're easily offended, you hate the f word, or you hate stereotyping then I would recommend not watching this one. Hell, it even stereotypes me a bit. Its probably the most famous scene from 25th Hour, a Spike Lee film, and many people agree this is probably the best monologue in a film. Then again, like every Lee joint, it takes place in NY where I'm from and all the people I know that say its great are all from NY as well, so we might be a bit biased as it may relate to what we know a little more, lol.
And there's a scene from Children of Men that I love, but can't find. (When Theo is taking Ki out of the building into the army crowd and stuff, towards the end)
The first two are from Suicide Kings, which has some great scenes. My favorite is Walken's speech while playing poker, but I couldn't find it on youtube.