I learned quite a bit from the LAB Canyon Conundrum book. There is a video with Dan Margulis and Bert Monroy on YouTube somewhere where he changes the color of a car in LAB. That might help those who have never used it to get a grasp. The main thing to be concerned with is that you can easily push things out of gamut, and you may end up with heavy ink densities if you head back to CMYK or other effects in RGB conversion. These are just some considerations to keep in your head, so it is good to read a book and understand the nuts and bolts of it before you go wild making pretty things on screen.
Here is the one I made in LAB. This is a really quick go, took only a minute. The newer Masking panel with refine mask edge did a pretty good job of the underwear texture--I'd fix it up if it were the real thing, but not bad. After I copied the background and masked it, I attached a curves adjustment layer to the masked layer to change the color and darken the luminosity. I grouped the masked layer with its curves adjustment and then copied it and set the copy to overlay to add more dimension. I then pumped up the contrast a bit more by copying the background layer(white underpants) and putting that copy on the top of the stack on soft light...not sure why I did that, wasn't really thinking, just had an intuition that it might look more realistic, but I probably could have accomplished the same thing with a curve. Then I added another curves adjustment layer on top and made an S curve in the L channel to darken the midtones more and increase contrast. Done.