The expression "following suit" is a curious one, because it has nothing to do with walking behind a matching set of clothing. If you follow suit, it means you do the same thing somebody else has just done. If all of your friends decided to jump off a bridge into the icy waters of an ocean or river, for instance, and you jumped in right after them, you would be following suit. You can see why following suit can be a dangerous thing to do, because you could end up drowning simply because somebody else thought of it first.