You'd guess this one had something to do with the clock: you're Evgeny Bareev, you're playing Black against Karpov, he has a slight edge all the way through, it's the occasion of his greatest performance in tournament chess.
Under those circumstances, you're going to be in time trouble. Bound to be. And as the screw tightens, with White's knights dominating the centre, with the White king looking rather better placed to get at your queenside than yours is to defend it, with six moves still to make before the time control, what are you going to do?
Your king can't do anything with the knights there, at least he can't fork you while it's there. But what else can we see, with the clock running down? Does a knight move let the rook into b5? Re8 allows something to d6...maybe h5, can we get away with that? Or we can exchange rooks, but is that going to end up stalemating the bishop?
That's how you're going to think in circumstances like that - time to see all the potential disasters, no time to see if any of them can be avoided. So what you do is try and make a move which, as far as you can see, in the time you have to see it, changes nothing.
It's the best that you can do. Except that it's the Worst Move On The Board.
[Worst move index]