Small adhesive nipple covers get used to hide the areola while still keeping the tits basically on display, usually in cute shapes like hearts or stars. The vibe is teasing and fetishy, with the stickers peeling off mid-fondle or during sex so the nipples pop free right before the groping and licking gets more intense. You’ll often see them paired with lingerie or idol/cosplay outfits for that “barely covered” look.