I said it once elsewhere, but it's still true. It's not marriages gays want, it's weddings. Any excuse to look fabulous and party all night.
Otherwise, everything that's the real purpose of marriage - monogamy, fidelity, lifetime commitment, and the raising of children - is directly contrary to the entire gay ethos and lifestyle. Promiscuous sex without responsibility is the defining element of homosexuality (at least of the male variety). Marriage is the defining element of heterosexuality, as it conforms exactly to what women want from men in return for sexual favors.
That is a very funny post. Quite true, but still very funny.