There is a custom among some tribes in Sub Saharan Africa called "dry sex" where the female packs her vagina with all kinds of things, including sometimes, soil. The practice has contributed to the epidemic of AIDS because the abrasion from sexual contact allows for transfer of the HIV virus into the bloodstream. It is my understanding that's only done to adults however, not children.
There are a number of cultures world wide that practice forms of genital mutilation on children intended to prevent sex before marriage. There is a global effort underway to educate against the practice.
I've never heard of anything like what you describe but there are a lot of people in the world, some with very unusual customs. It wouldn't be surprising if someone tried that.