(I’m a cook at a restaurant. A sandwich comes back rung up “No Mayo, allergy”. I call the server back to the kitchen.)

Server: “What’s the problem?”

Me: “So, what’s the guy allergic to? The eggs or the vinegar?”

Server: “What do you mean?”

Me: “That’s what’s in mayonnaise. Eggs and vinegar. If he’s allergic to the eggs, I’m going to need to get rid of two of the things on the sandwich. If it’s the vinegar, I’ll need to get rid of four. If it’s any of the other chemicals or preservatives or whatnot, I’ll have to leave off everything.”

(The server goes and talks to the table, and returns a minute later.)

Server: “He’s not really allergic to anything. He just wanted to make sure that it didn’t have mayo on it.”