Some people call them bullets and some traders call them conversions... but basically they are synthetic shorts.. and here is how they work:
You buy 100 shares of a stock and you also buy a put on the same stock. Now basically, you are flat because if the stock decreases in value the put you own increases proportionately, and of course if the stock increases in value your put decreases proportionately. This is basically called a synthetic short. Now, because the premium on the put is so high, most traders usually write covered calls on the stock (since they do own it), which helps to offset the cost of the put. Now basically, you have bought a put and sold a call on the same stock that you own. So essentially, if you sell your shares of the stock, you are, for all intents and purposes, short; but since you're not actually shorting the stock when you sell it (rather, you are just "effectively" short), you don't have to worry about violating the uptick rule.
If you trade the same stock every day, its worth its weight in gold. But remember, there are costs involved in setting this up (the put still costs you money even though you've offset the cost a little bit with the covered call, and of course, you usually have to pay interest on the underlying stock which you have to own until you're bullet/conversion expires).
I hope that helps. Let me know if you have any more questions...