It is indeed a wrong idea or belief held by some people; there is no basis for it in the sources or authentic fiqh. All that is required, after sexual intercourse, is to wipe oneself clean, wash the spot where semen has fallen and take a complete bath with the intention of ridding oneself of the ritual impurity. Simply toughing something in a state of impurity would not render it impure. How can we say so, when we learn from the Prophet’s beloved wife Aishah, may Allah be pleased with her said, “Once the Prophet, peace be upon him, ordered me to get him something from the mosque, and when I excused myself saying that I was menstruating, he said, “your menses is not in your hands!” In other words, the ritual impurity of a menstruating woman or a person in a state of sexual impurity is not passed on to the people or objects they come in contact with. So there is definitely no need for you to wash the linen or clothes you have touched in a state of impurity, following intercourse or menses.