heyo: If both players pass again consecutive all stones are treated as alive and the score is computed.
No idea can be posted without it being shot down. :-) One problem with this rule is that novice players often mark dead stones incorrectly because they don't understand how to do it. The first time this rule was used against them, a lot of them would just give up.
Also, there are tricky positions that are difficult to figure out. These would require some discussion between the players and possibly multiple attempts to mark the stones.