In bball, a brick is a missed shot, typically a knuckleball, too hard, and lacking in arc, which has that distinctive clang/thud off the rim. Applying that to pinball, your shot clangs/thuds off of a post/some other structure causing you to miss your intended target (e.g.ramp). I have sequences in MMR where I am able to score an impressive number of consecutive bricks. If you ever got points for hitting those effing black posts, I'd be setting world records!