What to do with unpaired stud earrings?
Until mainstream fashion embraces people wearing one earring again like they did in the eighties, here's another more practical idea.
Ditch the post and use the earring as a push pin. You can trim the post back by using wire cutters. It's not as strong as a push pin but works to hold one sheet of paper.
It also can be prettier than the plastic push pins and you now have an excuse to hang onto them for sentimental reasons.