Quite possibly the most effective and dangerous insult to use against someone. Has the vulgar power of 5 billion nuclear suns inside and has the potential to end the target's career, dignity or even life. Should always be used as a final blow, if things get too out of hand.
Adding the word 'lol' at the end of the phrase enhances its power and signifies how your target's mother's state of homosexuality is amusing for you. You mock your victim's weakness. You're basically a god when you say it.
Opponent: "you're a goddamn nuisance and you should never have been born"
You: "your mom gay..."
*universe holds its breath*
You: : "...lol"
*universe implodes*