Descent into Philadelphia from San Jose, Costa Rica. Came in from the north, along the Delaware river, and got caught in the jetwash of a DC-10 that we were too close to. The plane banked to the left (where I was sitting at the window seat), so I was looking straight down at the Delaware, and suddenly dropped--I don't know, 100, 200 feet? I was scared shitless, thought it was over...and thanks to that, often use valium when I fly!