Two men and two women, each suffering from different sexually transmitted diseases, now only have two condoms, requiring each man to have sex with each woman and not to infect each other. How to use condoms?

Answer: At first, a man took two condoms at a time, and a woman and a woman took off one. Then another man and a woman take the first man's jacket, and then another woman takes the other.

Understand?

One side of all condoms is always in contact with only one person.