No, not T-shirt AND underwear - but, a combo of the two. You can make your own underwear out of your old t-shirts. Just apply this pattern to your favorite, worn-out tee to make yourself a set of homemade, couture undies.
If that's not enough, there are also companies that let you personalize your own undies:
DIY T-Shirt Underwear
13,876 clicks in 286 w
More Stats +/-