I would not suggest trying this, no matter how comforting the knowledge that you will not be breaking both hands tomorrow may be. However, I will try to come to some conclusion about how optimism like this could be used.
While most normal people use optimism to cheer people up, there is always the possibility that it will not work. This is because the recipient of the optimism may realize the ploy of the optimizer (used here to define the person who offers optimism), and resultantly assume that the opposite must be true. One might say this is a fault of humanity. We assume that others would only be kind to us if there was something so terribly wrong that they had to soften the truth. On the other hand, this is often the case.
The classic example includes the patient in a hospital who is dying of an incurable disease. Unfortunately, the patient does not know this yet and some doctor or nurse must take the responsibility of telling the patient (unless of course they opt to tell the patient’s family first and suggest that a family member break the news; this is more commonly known as the “chickening out”). The doctor comes into the room and makes himself comfortable before making some completely random side-note to lighten the mood, usually something along the lines of “It’s such a beautiful day outside. Did you look out your window?” or “You know your parents love you more than anything in the world.” Almost immediately, the patient replies, “I’m going to die, aren’t I?” Afterward, it can be agreed that everything would have turned out better had the doctor just chickened out.
The best way to negate the possibility of being discovered is to make it impossible for the recipient of the optimism to tell if you are serious or not. They will be too busy trying to figure out your point to think about whatever might be wrong. There is also the chance that the absurdity itself will be funny, in which case simple optimism can’t even compete.
Considering the sense of looking to tomorrow for a day better than today, I think that humans are cruel to themselves as when assuming that others must be lying. We say tomorrow will be better, but by the time tomorrow comes, we have already forgotten that we were hoping for a better day the day before. As a result, we spend most of the time hoping that tomorrow will be better than today and not enough time deciding if today actually was better than yesterday. Simply noticing that you have not broken both hands today after breaking one yesterday offers a limitless geyser of delight, whether it is because today actually is better than yesterday or because you considered the possibility of something impossible actually happening.
Concerning telling a dying patient that, if the patient dies once today, the patient won’t die twice tomorrow, I can’t be certain of the outcome. Seriously, that takes the issue to a whole new level. Unlike the quote, it neither makes sense nor offers any really consolation about tomorrow. I have to admit that it’s still a pretty funny thought.