I've been on Free Republic for a long time and this is a silly question, but what does "Bump" mean?
Well,it is just that. . .a bump up the thread and a 'flag' of sorts to call attention to the post. Sometimes people do not have time to respond but feel it important enough to offer a kind of 'I'll second that' or just want to boost post visibility and so the
bump.
Also helps if you want to personally flag post as well, so that it is in your comments file and easier to retrieve when you do have more time.