Earlier quoted context omitted.
Lol! I did that (sometimes) when I was in hospital in the UK. If you requested a halal meal they sourced it from a takeaway down the street, which was excellent, and a wonderful break from the usual dismal fare. I wasn't a dick about it, and would ask the meal order folks if it was OK to request one that day; sometimes they said 'yes', and sometimes not (based on what, I don't know), but they knew what was up, and di…
Supposedly this "trick" works on airline flights, too.
most airlines that fly long routes offer a ton of different menus: kosher, halal, vegetarian, vegan, asian vegetarian (my favorite - usually indian food, which still tastes good when microwaved as opposed to a lot of non-first-class airline meals), lactose-free, gluten-free, diabetic-friendly... many options available that are usually a cut above the typical "chicken or beef".
beware - you have to do this for each leg of a flight with layovers! i've occasionally had luck requesting a vegetarian or vegan meal in-flight but most of the time they only pack as many as are requested ahead of time.