If you go to the aforementioned cool site, ThinkBeforeYouSpeak.com, among other nifty tidbits of info and resources around homophia, they keep a constantly running ticker that tallies the number of times "that's so gay," "fag," "dyke," and other homophobic slurs are used on Twitter. At the time of my writing, "dyke" has appeared 927 times today, and mentions of "fag" and "that's so gay" capped out at over 1500 times each. Alrighty then.
In addition to those 'expressions' (if that's what you wanna call them) being all kinds of homophobic and generally ignorant, folks should also know this:
When you say "that's so gay," this is what I hear you really saying: "I'm not actually all that bright."
When you call someone a "fag", or "dyke" or "queer" (after seeing red), this is what I hear you really saying: "I'm not actually all that bright, and on top of that, I'm hateful and mean-spirited."
(Yeah - I know you're 'just joking.' Yeah, I know 'we can't take a joke.' Yeah, you do 'just have to be so politically correct all the time.' And it's, like, such a drag and such a hardship, and blah blah blah.) Here's the thing: you don't get to play the 'just kidding' card when you put other folks down. Doesn't work that way.
So please. Do us all a favour and stop telling us how dumb you are. Stop telling us how hateful and ignorant you are. We get that stupidity and ignorance exists, we just don't think you need to shove it in our faces all the time.