Absolutely No Substitutions

I saw this in a cafeteria the other day and it cracked me up.

I wondered whether it was no substitutions because that would, clearly, not allow them to say it was 500 calories anymore. 

"Hi, yeah, I want the 500 calorie meal.  But can you add extra mayo, extra cheese, some of that special creamy sauce, extra meet and can I substitute French fries for carrots?  That's still 500 calories, right?"

Or if there was some other reason.

"Hi, I'd like that meal, but in place of the sandwich, can I get sushi?  And in place of the carrots, how about that cheesecake delight?  And water...hmmm, I think I'll have a beer.

Either way, it made me laugh.