Did you know that the food you eat every day has been handled by gays?
That the medicines you take when you're sick are, in part, made by gay people?
That you probably bumped into a few gay people on the street this last week?
That you probably shaked the hand of a gay person on multiple occasions?
That at least one of your close relatives is most likely gay?
That, yes, there's a good chance that one of those blood donations your family has gotten could have come from a gay person?
In short, did you know that there are a lot of gay people in the world and that you don't know it because they are mostly, with the exception of their gender preference, just like you and me?
Clearly, the only way to avoid them is to never leave your basement.
Edit: Having read Sussi's comment, I remember in my country, the Red Cross also prohibits gays from donating blood, which is kind of strange given our otherwise tolerant look on homosexuality.