What is it about people that makes us buy clothes that are too tight just after we've lost a bunch of weight? I don't normally like or buy tight clothes. Thin me didn't ever wear tight clothes. Fat me only wore them when she was in denial about how fat she'd gotten and didn't want to buy that next size up. Newly average-ish (I still feel heavy, but I guess I'm average) me buys stuff just a little too small to look good. I've still got quite a belly, so the tightest shirt I can squeeze it into doesn't look good. Yet, this is what I bought.
I don't think this is unique to me; I've noticed it in others. It's like the thrill of fitting into mediums overrides the good judgment not to wear them just yet. I'll look all right, as long as I don't sit. :)