Most of my cotton pajama pants have drawstrings, and they're freaking annoying: I have to tie and untie them every time I go for toilet. And I believe this quick-release clip can solve that problem. Best thing is, when it lie inside the waistband against the skin, you won't even feel it's there!

Haven't tested it on shoestrings, maybe with just some small alteration it can work well on them as well.