A classic film moment... this is a personal favorite of mine. Two things of note: One, the laughter is real. Benicio was fooling around with this character, who was supposed to be a bit part, and making everyone laugh during the take. The character ended up getting more screen time because he was so great with it. Two, you can't see it in this YouTube clip, but in the original cut you can see a boom mic coming in from the top.
Enjoy. NSFW if you've got speakers on.