Some of the shirts that are shorter in the front and longer in the back end up looking like the shirt has a butt flap. I've taken to calling them "butt flap shirts" and when I'm shopping I'm like, "oh cute, but ugh, butt flap!"
"I don't know! I don't know why I did it, I don't know why I enjoyed it, and I don't know why I'll do it again!" -BART SIMPSON