You always want what you can’t have — especially when it comes to beauty products. That’s why we’re getting the inside scoop from your favorite retailers on what’s selling out right now, how to sign up for waitlists, and where to go to find the next best thing. Because if everyone’s buying it, you know it has to be good. coworker of mine once described that effortless stain that's left on your lips after you've, say, kissed a stranger or polished off a popsicle, as Lipstick Nirvana. "It's that moment when the pigment on your lips has faded quite a bit...[and] leaves behind a ghostly stain that looks amazing," she said. There are many lipsticks on the market today that claim to produce those coveted results, but none are quite so compelling as the color-adapting ones — or, mood-changing lipsticks , as we like to call them.Lipstick Queen's Frog Prince is one of those chameleon-like products. Yes, it looks ghastly green in the bullet, but once slicked on, it turns into a beautiful, rosy pink. As it turns out, this lipstick is one of Birchbox's most popular products. In fact, since the retailer introduced it to virtual shelves in July 2015, it has become one of the store's five best-selling lippies.If you're wondering how that green bullet manifests as a romantic tint, I'll give you a mini science lesson. A dye called Red 27 is behind the magical green-to-pink transformation. "[It's] a red dye which is colorless when dissolved in a waterless base," explains The Beauty Brains , a website run by cosmetic chemists Randy Schueller and Perry Romanowski. "When it comes in contact with moisture, the change in solubility and pH causes the dye to turn bright-pink," the site reads . "The product appears to change with your personal chemistry because the color changes when it comes in contact with moisture, [which] can come from your skin or even just the humidity in the air."Last month MAC launched its own color-adapting lipsticks, and today, Maybelline has officially joined the club. Just a few hours ago, the brand announced the release of the color-changing version of its cult Baby Lips balm.Okay, so these lippies may not technically be adapting to our moods, but the results are still gorgeous enough to boost our spirits. If the stock of Frog Prince is wiped clean before you can click "buy" or you just can't wait for the release of MAC's new collection, we've tried a number of other color-enhancing lipsticks with similar attributes. Check 'em out in the following slides.