The worst gift I ever got was when I had just turned 13, and was just beginning my struggle with anorexia. Bear in mind that I was a thoroughly average sized child, on the stockily built side, but actually on the lower weight side of average. My stepmother bought me a gift for the family gift exchange - a pack of XXXL granny panties. I had to open them in front of the entire extended family, and when I protested about the size, she told me that I would grow into them soon.
The best gift also came that year, and was the Star Wars Encyclopedia.