You have no concept what's symbolism.
Many people are gay, but are in the closet. Many are married with children, and are grandparents. Many struggle trying to look "normal". So they remain silent. Hence, "Day of Silence".
It's not about stopping gay jokes, because obviously many gay people have a GREAT sense of humor (including me). I've called some people on this board, including the mods, "queer" more then a few times, although I always do it in joking and loving way.
Have your joke if you want to. That's what makes life fun.
At least understand that there are many types of people in the world who struggle with identity, and that includes gays.