Drainwalking is a special way of walking in a circular style drain that is used to avoid getting your feet wet or stepping in some other unpleasant substance that might be lurking in the flow of a drain pipe.
To drainwalk, one simply walks bow-legged, legs at an uncomfortable "^" shape, in an effort to avoid walking at the bottom portion of the drain. This gets very uncomfortable and sometimes even painful after a long period of time.
MacGyver adds: A different type of drainwalking is performed for the same reasons as mentioned above, but can be much less uncomfortable and allows much faster travel (so long as you don't slip). When bowlegged drainhobbling is too painful or the stream is too wide, try this method:
Take three steps (right, left, right) on the right side of the stream, then take the next three (left, right, left) on the left side of the stream. Repeat. Once you get the hang of it, your momentum can be used to walk right up on the curved wall to some extent. As soon as you begin to tip over by standing diagonally on an angled wall, you are already moving your feet over to the other side to reverse the process.
When you get moving, you can actually cover ground much faster than hobbling or walking in the stream can allow. If the walls of the pipe you are in are slick or too irregular, slipping or misstepping can be a serious hazard. I've slid and dunked myself in mystery liquid a few times by doing this, so think twice before trying it while carrying fragile/expensive or water-sensitive equipment (or if you are likely to break a hip or something)