I think Antonio was trying to say that gay people don't use "straight" the way straight people use "gay"--as a synonym for stupid. I personally have never heard a gay person say "Ugh I hate work...it's so straight!" or "it's so hetero!"
(because we all know gay people have more class than straight people, fact.)
"straight" has definitely changed in my lifetime. Well, it has always meant the shortest distance between two ordered pairs on a Cartesian co-ordinate system grid, technically, but in the vernacular it always meant "doesn't get high" or "isn't cool about it" back in the 80s. Like, oh, dude, there's my brother, he's straight. Put out that spliff and open a window quick! Nowadays, straight more often means heterosexual.
Gay, on the other hand, has always meant either happy (as in "Don we now our gay apparel") or homosexual (as in, my brother's gay, so stop trying to set him up with your sister.) It can also mean effeminate (as in, dude, that French press is so gay, why don't you just buy a coffee maker?) Maybe that's the way the kids are using the term nowadays to mean stupid. Then again, what does stupid really mean? Either way, I wouldn't worry too much if the word gay is being used to mean homosexual or stupid. This is slang. You know, the Brits objected to Curious George back in the 1940s, when H. A. Rey first published it in New York, so he didn't catch on in the UK the way he did in the US. Why? Because, of course, the word "curious" was 1940s UK slang for homosexual (or effeminate). These slang phrases are just what they are. Don't loose too much sleep over it.