1) Despite the way you're acting, this isn't actually happening to you
Sometime between going gluten free becoming trendy and doctors misdiagnosing Celiacs / gluten allergies, the unaffected developed a disdain towards anyone who mutters a word about being G-free. I understand that it may be annoying for you to be in the presence of someone who is on what appears to be the latest fad diet, but it's even more annoying for me. Because I'm not on that new fad diet by choice. And I really want that damn doughnut. That damn doughnut that you have the ability to go right out and get as soon as you're done being condescending to me.
2) And what is happening actually really sucks
The fact that my body declares war on itself and attacks my vital organs whenever I eat gluten (or just gives me horrible stomach pain or diarrhea which makes the rest of my day actually suck) is not cool. It's definitely not trendy. And it's not something that gives me great pride to announce. So please don't make my sucky situation even suck-ier by being a jerk when I kindly ask you to double check how my food is going to be prepared.
3) When you say "a little bit won't kill you", you actually don't know what you're talking about
The severity of gluten allergies varies, and if you're one of the lucky ones who have full blown Celiacs, then eating "just a little bit" of gluten can actually have some potentially life threatening risks. Like cancer. Ever heard of lymphoma? Untreated Celiacs are at high risk for it the second any gluten enters our blood stream and activates that body declaring war on itself and attacking vital organs thing we talked about earlier. So no, "a little bit" of gluten isn't going to kill me (right away) but I'm not risking my life to make yours no different at all.
4) We're not actually afraid to tell you off when you're being ignorant
We've had to learn how to be tough. Resisting the Pizza Hut that all your drunk friends just ordered and turning down your favorite family baked good is freaking tough. So if we can do that, we can sure as hell stand up for ourselves when someone gives us lip about our own bodies. Whether you're a lazy server who just wants to go home and not take the two minutes to double check with the chef or a self righteous pharmacist who has been filling this prescription for years and swears nobody has had a reaction, you're going to get told off. And it's going to be good (for me) because I've got this speech down from having to give it so many times.
5) Just like you, we actually wish we'd never heard of the phrase "gluten free"
There's nobody that gluten pisses off more than the gluten intolerant. Our lives just got considerably more frustrating through no fault of our own, and we would do anything to change that. But we can't, so we ask for a little bit of compassion and at the very least respect from those around us as we figure it all out.