Sunburns often strike where skin meets bathing suit. Sensitive and hard-to-reach spots you've neglected to smear with suntan lotion (along bikini lines, underneath buttock cheeks, or around the breasts and armpits) often fall victim. These burn spots then have to face daily irritation from tight elastic in bras and underwear. To ease chafing, cover the burned area with a dusting of cornstarch. Don't apply petroleum jelly or oils, which can exacerbate the burn by blocking pores. If the burn is blistering, however, don't apply anything.