Ya know, there are many reasons not to have unprotected sex, including unplanned children, financial strain, and STDs. But STDs aside, allow me to offer you another reason not to have unprotected sex: some people don't wash well.
The need for vaginal cleanliness speaks for itself, but men have various crevices and folds that need to be addressed, too. Some men just splash water on it and go, thinking it doesn't need special attention because it's not a vajay. Well sir, it does because currently---it's a bacteria factory.
This has been a Public Service Announcement, brought to you by Lucas McKenzie.