OK, I'm using bonanza to mean any extra financial "bonus" you get beyond your regular income. The most common one for people in the US is probably a tax refund, bonus at work, or an inheritance. The problem with these is people often think of this as "fun money." Even worse, I know a lot of people who spend twice as much as they're expecting---before they even get it---then wonder why they're so short after they get it.
Instead of thinking of this money as a freebie to spend on frivolous "rewards," this is exactly the money that should go to either paying off consumer debt or toward your financial cushion. Where normally you try to save between 5 and 25% of your income, think of this money in the opposite. Take 5 to 25% of this money for "fun" and the rest should pay down debt or go into savings. If you have little debt and a healthy emergency fund, take 25% to play with. Be honest about your finances though (honesty is absolutely the first necessary step to getting money under control). If you have debts that are pinching you month to month or little savings, only take about 5% of this for fun. If you're truly on the edge, you may want to consider not touching any of it. Even if you have a well-funded emergency fund, a truly stable job, and no debt, putting at least half of this away (maybe into retirement) keeps a good habit in place.
It can come in other forms too, of course. If you aren't salaried, it can come as pay for extra hours, even overtime, or you might sell something (you just discovered a rare and valuable thingummy in the attic), or you might get a bit of extra work (your second cousin paid you $200 to keep their kids for the weekend). Again, DON'T spend this money before you get it, and definitely don't spend more than you're getting. Pay your emergency fund or debts first, and keep a responsible amount for fun money.
For instance, I got some extra hours this past week. I'd known I'd have some, but I was only expecting about $40 worth and was not planning to touch any of it. Instead, I worked about $120 (after tax) extra. Now, my income is pretty low because I'm a full-time student and during terms, I can only work part time. But I have an emergency fund and no consumer debt. So 5% of $120 is $6. I thought about it and decided that for ME, the most bang for that money in pure pleasure was buying really good gourmet coffee several mornings before work. It may not sound like much, but I really do love good coffee, and I got a lot of pleasure out of doing something I normally can't, more than most people get out of a fine meal at an expensive restaurant. Sometimes, luxury is a matter of perspective.