Among the NFL documents unsealed by a federal judge in the Tom Brady "Deflategate" appeal is a fact sheet on HIV and AIDS given to all players. And the document acknowledges that some of its players may have sex with men.

Deadspin uncovered the fact sheet and it's common sense information that is nonetheless important for players to know, whether they be straight, gay or bi. Here are some passages that mention the risks involved in certain sexual practices:

How does someone get HIV infection?
The most common way to get HIV is from sexual contact. The virus lives in fluid from genitals (semen from the penis and vaginal fluids) and in blood. The virus can go from men to women, women to men, and (rarely) from women to women. Although transmission from man to man by anal sex has been most common in this country, it’s now becoming common for men and women to give HIV to each other. That’s been true in other countries for several years. …
Can I get HIV from having one sexual contact with someone who is infected?
Yes. Even a single contact has some degree of risk. The risk is even greater in certain situations, such as when either person has a sexually transmitted disease (like gonorrhea or syphilis) or if the HIV-infected person is sick with AIDS. Having sex with many partners increases the risk of infection because you increase the chances that one of the sex partners will be infected and they themselves may have multiple sex partners. Latex condoms decrease the risk in vaginal, oral, and anal sex. Anal sex, whether between a man and a woman or between men, increases the risk of infection because there is a greater likelihood of tearing of skin and bleeding.
What is safer sex?
Safer sex is behavior that prevents sexual partners from becoming infected with HIV virus. Not having sex is the safest behavior. For many people, a more realistic approach includes relationships in which both partners are monogamous, meaning they do not have sex with any other people. In other situations, for greater safety latex condoms must be used during sex between men and women and between men and men. Condoms don’t give 100 percent protection but they help decrease the risk of HIV transmission. They protect by being a barrier. To be effective, the condoms must be worn for the ENTIRE duration of EVERY sexual contact. Petroleum jelly and other oil-based lubricants should NOT be used because they increase the chance that condoms will break. Natural condoms, such as lambskin, are not good barriers because they may have tiny holes through which HIV can pass.
Is anal sex safe?
No, anal sex is even riskier than vaginal intercourse because there is a greater likelihood of skin tearing and bleeding.
Is oral sex safe?
We don’t know, but it is less risky than intercourse. Whatever the risk is, it is present regardless of whether the oral sex is from woman to a man, from a man to a woman, or from a man to a man.
Can I get HIV from kissing someone who is HIV positive?
No. Although small amounts of HIV are in saliva, saliva has been found to inhibit the virus. Therefore, the small amount of HIV that is in the saliva is insufficient to cause infection.

The information is included in the league's manual for players, and I bet few actually read it (like most employee manuals). The government estimates that 50,000 new HIV infections occur each year so the more this information is out there, the better.