1. Wet the underwear, then apply the toothpaste you usually use, gently rub it with your hands, then leave it for a while, and then wash it with transparent soap. Finally, wash it with clear water several times.

2. Both human sweat and secretion contain water-soluble and salt-soluble protein. What turns yellow is actually denatured salt-soluble protein. If you want to clean it, you can add a proper amount of edible salt or rinse it with normal saline.

3. Underwear hand washing is relatively clean, but the disadvantage of hand washing is that the detergent can't be washed clean and can't be completely wrung out after washing. If it is really clean, it can be boiled in water for 15 minutes.

Underwear needs to be dried in a ventilated place first, and then don't disappoint the kindness of the sun. Ultraviolet rays in the sun can sterilize and keep underwear hygienic. I'm really embarrassed to let my underwear bask in the sun, so I have to dry it thoroughly with a dryer. Underwear is clean and refreshing, and I will be comfortable to wear it. In addition, in order to wear comfortably, women had better choose cotton underwear. Note: If exposed to the sun directly, it will deform and harden.