There are some things in this world that I will never understand, like string theory, the appeal of Brussels sprouts and how “Two and a Half Men” is still on the air. I accept that I don’t understand — I know I will never get it, and I will leave these things to the people who can comprehend them.

One thing I don’t get and refuse to accept, however, is why the word “gay” has entered our collective lexicon as a commonly accepted synonym for “bad.” I do not understand it and I never will understand it. Unlike Brussels sprouts, I cannot let it be.

I hear people refer to negative things as “gay” on a daily basis. I have friends who say things along the lines of, “It’s so gay to have class on Fridays,” or, “You’re not coming out tonight? Gay!” Nine times out of 10, I will sit there and not say anything because I don’t generally like to cause drama about small things.

But this is not a small thing, and I should not stay silent. I’m going to tell you, dear reader, just why this is unacceptable.

First of all, it doesn’t make sense. Think about it: Why is being gay bad? Why does it have a negative connotation? It’s the same as being short or tall or a redhead. There are gay people in all cultures, all levels of society, all races, religions and countries (except, supposedly, Iran). Being gay is … normal.

True, not everyone is gay, and modern American society is not the most gay-friendly in the world. But this is 2010. Would you say the fact that the cable guy can’t come until next week is “black?” Would you say that forgetting your umbrella when it’s raining is “female?” Of course not. There’s nothing wrong with being African-American, just like there’s nothing wrong with being a woman, just like there’s nothing wrong with being gay. The negative connotation is completely unfounded.

Every time you say something you don’t like is “gay,” you are making that negative connection. You are taking something perfectly normal and, frankly, unremarkable, and attaching it to being negative. Every time you use “gay” like that, you are tying being gay to being bad.

“But wait!” you say. “I have gay friends! I’m not a homophobe!”

Well, you might not be a homophobe, but you certainly sound like one. Do your gay friends know that you think that part of who they are is negative? I know that if I found out my friends thought being short was bad (or worse, immoral), I would hightail my 5-foot-2-inch self right out of their lives. No one wants to hang out with people who disapprove of a central part of their being.

“No,” you say. “You’ve got it all wrong! I don’t think being gay is bad!” Then why on earth, gentle reader, do you keep saying it is? Every time ­— every time — you use “gay” to mean “bad” or “dumb” or anything else negative, you reinforce the idea that being gay is bad. If you don’t think being gay is any of those things, if you don’t care what consenting adults do in the privacy of their own homes, then it is just plain ignorant and hurtful to insinuate otherwise.

I know it’s hard to change your vocabulary. I know what it’s like to develop a catchphrase and use it over and over until you can’t remember a time when you didn’t say it. But “gay” isn’t “hella” or “whack” or a “that’s-what-she-said” joke. “Gay” as a pejorative is hurtful, offensive and ignorant.

If you can’t bring yourself to stop using “gay” in a negative light for me, stop using it for Cody Barker, an openly gay teenager from Wisconsin who killed himself in September after being bullied for his sexuality. Or stop for Billy Lucas, 15, who didn’t identify himself as gay but who was tormented about his perceived sexuality so badly that he, too, took his own life. These young men died because being gay was perceived by their peers as being bad.

Being gay is not a negative thing. Love is not a negative thing. Stop implying otherwise.