When you screw them both up and have to rip them both out. Yes, I thought I was being all sensible by adding some stitches to both the fronts so that it would be wide enough to close over my belly. Of course, I forgot that I had already decided to knit a larger size. Doh! The ribbing part looked to be the perfect width. The two fronts looked perfect. I kept draping them over my torso admiring their perfectness.
Then I realized--wait, I still have to pick and knit the button band. Double Doh!
So, back to the frog band. Oh, did I mention I had screwed up a cable on side and had ripped and re-knit once already on one front?
To console myself, I finished my tropical Interlacements Tiny Toes socks.