Noun - A person of any sexual orientation who constantly demands that people acknowledge and accept homosexual sex as normal and equal in all respects to straight sex, irrespective of another person's religious views or whether the issue is appropriate to the circumstances.
(1) Jennifer's baptismal ceremony was spoiled by her muckspammer Uncle Ted, who yelled at the Catholic priest and called him a homophobe because he talked about the union of Jennifer's parents during his homily without mentioning same-sex unions.
(2) Dude, we're eating; stop being a muckspammer. I don't want to hear about your latest gay sex conquest. You're my friend, but when you talk about your sex life, I want to throw up.