It was very difficult to decide a favorite UB moment, but this Running Man episode cracks me up. Starting at around 10 minutes is the first challenge. I apologize Taecyeon (I was told he has looked at cards on here in the past), but this is really funny. It shows how strong he is but also how much of a good sport Taecyeon is (and competitive).
This is only the first part of the Running Man episode. Dramafever.com has the whole episode, which I think is worth watching.