An unintelligent person who is intolerant of others' choices or culture.

Something that is not sensible and unsatisfactory. Something that is derogatory and insulting and dangerous to human kind. The opposite of Yog

Yag is "gay" spelt backwards, evidently describing someone who is homosexual, but dispises the "gay scene".
A backwards gay person, "yag" someone who doesnt want to conform to the "gay scene". Or rather, a gay person who HATES gay people.

a closet gay guy, telling about himself on the net, without disclosing his identity

Just like LOL means Laugh Out Loud, YAG means You Are Gay.

Mr.Wickhams way of making fun of people who use the word gay, not meant to be offensive, but meant to be used in place of gays overuse

Meaning "gay", often used in a derogatory manner.