This is sort of a "give me back my toothbrush" line, but instead it's "keep my pretty dress, okay!"
That dress, that t-shirt, those shoes you left your ex with can become a symbol of something so much bigger—especially if the ex looks just as good as you in them. It's widely known that "One More Hour" is a break-up song that Corin Tucker wrote for the other singer-guitarist in the band, Carrie Brownstein. They met as young riot grrrls in the mid-90s and connected through music (by the way, for those wondering how it is that they dated, when Corin Tucker is now married with two kids, she is bisexual). Presumably they were swapping songs and cool clothes the whole time they dated, but we're also assuming Tucker is using the dress and the shoes symbolically. These superficial things are the remnants of a once-rich relationship.
Tucker's heart-wrenching refrain goes out to everyone who's been subjected to an "other girl" situation.
In some ways, this song is the epitome of tragedy. But its defiant tone reflects the power that emanates from so much of Sleater-Kinney's work. Though it is often vulnerable and open, their music is never about sitting back and taking it while someone screws you over. By demanding silence about the "other girl," the singer seems to gain some power. That doesn't make the line less sad, but it makes it more powerful. And it must have all worked out somehow or other—after all, Sleater-Kinney stayed together even though Tucker and Brownstein didn't.