Now why are these hairs curling back into the skin? Lots of reasons, actually, but it mostly has to do with the irritation of the hair follicle, which can come from waxing/shaving/tweezing improperly, exercising a lot, and even wearing tight clothing. "As you're moving around all day the tight underwear is rubbing against the skin, and of course, the skin is beginning to get irritated," Jodi Shays, aesthetician and founder of Queen Bee Salon & Spa , says. "Not only will the follicle react by swelling, but then it traps whatever's in there, like the hair, and that's when it can curl in." The follicle can also get disturbed and cause an ingrown hair if there's oil and dirt buildup on the skin, which can actually be prevented with routine body exfoliation and moisturizing.