What is Gaycism?
1.
Racism against homosexuals.
"My God, Matt! Your gaycism is disgusting, don't ever talk to me again!"
See
2.
"Being racist against Gay people"
or being homophobic, being discriminatory towards homosexuals and/or lesbians.
When Tommy didn't invite his gay friend to the cookout, he knew he was commiting an act of Gaycism.
See