Amazing that Michael's "you taught me a lesson not to teach lessons?" still makes me crack up every time. While not my absolute favorite episode since it's sort of a "one note" episode, they really got maximum mileage out of that one joke, and Pier Pressure remains a fanastic episode where everyone had a small part, and played it to perfection.
The attention to detail is startling; the three-legged dog, the notes, the sandwich grabbing. And one aspect that really makes this episode for me is the wonderful faux-suspense music during the entire drug deal.