Men who have sex with men are subject to a lifetime ban on donating blood. The U.S. Food and Drug Administration implemented the ban in 1983. Now that you are aware of this ban, don’t show up at a blood drive, then get surprised that you need to bow out of making a donation, or worse, lie about your sexual history and donate blood anyway.
This policy is controversial. Most major European countries recognize that your blood can be tested for HIV antibodies, hence those countries limit donors to men who have sex with men in the past one to five years. But while the FDA ban remains, you should decline the opportunity to donate.