Another name, coined it seems by students, for lazing around spending money and chatting all day, instead of actually doing any work :-)
But actually it's really quite fun... When I'm sitting in a cafe with friends, we are (more often than not) discussing work or projects of some sort. Its the yahs that are the irritating ones, they seem to take over the whole place, try to squeeze a large number of chairs round a small table and then complain loudly in pretentious upper class voices about how daddy would simply not have this, and would have the riff raff thrown out..
OK, maybe I'm exaggerating a tad here, I really quite enjoy sitting around and relaxing with a drink in somewhere thats not a pub. The yahs are bad, but maybe not quite as bad as I make out sometimes, but they are incredibly stupid. If you know where to go, and where to avoid then you can find yourself a nice peaceful cafe just for a small group of you :-)
Edinburgh has hundreds of cafes, or so it seems, catering to those with more money than sense right down to those with their last few pennies to rub together! And with the city so full of students I think they sprung up to take advantage :)