Don't wear underwear for a month or two, okay?
Not wearing underwear has advantages and disadvantages. If it is good to wear underwear at night, it can help blood circulation and provide a good sleep, but not during the day. From China's point of view, this is too exposed. From a medical point of view, it is unsanitary, easy to get sick, and the chest will sag for a long time because of gravity and other factors.