Minnesota nice: "I’ll have the fish, but can I get chicken instead, no garnishes, and a bun with cheese?"
Translation: I don’t like this menu at all.
A minor substitution here or there, or asking the kitchen to leave off an ingredient, isn't a big deal... sometimes. Believe it or not, restaurants go through a lot of work preparing the menus. If you’re going to ask for substitutions, omissions, or additions, at least try to be respectful about it. Don’t order something and then request enough changes to completely transform the dish into something else.
If, for some reason, you find yourself at a restaurant against your will, and there’s nothing on the menu you think you can reasonably choke down, ask the server if the kitchen can accommodate a special request. Don’t try to magically craft an entirely new dish through word wizardry.