I ordered a Tshirt from Cafepress and I ordered a small. I, of course, cannot actually wear a small.
So I got the shirt, realized that even if I were in 6th Avenue shape I wouldn't be able to wear it, and wrote to them saying "Derp. I either ordered the wrong size or I was accidentally sent the wrong size" (I couldn't actually tell at the time but since then I've become assured by looking at my original order confirmation that it was my fault.)
When you get customer service like that you're supposed to blog about it. So I am.