The Hole Truth

Here's a question you don't want to think about: How big can a hole get in your sports briefs before you just throw them out?

I have several pairs of sports briefs I wear under my shorts to the gym or when running. Nobody sees them. There is a hole in one of them "underneath", between the legs. Even if you were to watch me getting changed (and please don't) you would not see the hole. The hole is getting larger, but for now the structural integrity of the briefs remains intact.

At what point do I just throw in the towel and get rid of them? Does it matter?