Let's be real here, ordering anything from a fast food restaurant usually isn't healthy (even if it says it is). Logically, everyone knows that fast food isn't nutritionally good and should mostly be avoided because of that, but it's not always bad because of the calorie count.Sometimes fast food items are bad because of the way they're handled or kept either before or after being made. A thread on Reddit (an online forum for any topic for people around the globe) focused specifically on this. A user asked what fast food workers would warn their customers about and boy did they deliver. Workers from chains like McDonald's and Burger King all the way to Taco Bell and Domino's chimed in to warn unsuspecting patrons of the gross fast food practices each restaurant took part in. This is apparently a problem that spans fast food chains of all kinds, though you'll notice a few key repeat offenders on this list.The workers specifically talked about what exactly a customer should never order from their restaurant. Either because of gross practices, never-cleaned machines, bad ingredients, or just general unhealthiness, most places always have at least one thing that a customer should never order. So, here's a compilation of some of the top answers from that Reddit chain, as well as some other interesting ones scattered across the internet.Warning: this will alter views on the globes popular fast food chains. Be prepared to be grossed out.