Stupid vs. Ignorant

Today I watched someone ask a question at a sandwich shop, S****Y, that made me realize how stupid people can really be.  Let’s start with the definition of two words that one may be mistaken for the other.

Used as adjectives

Stupid: Lacking intelligence or common sense.

Ignorant: Lacking knowledge or awareness in general.

I was standing in line telling the nice person what I wanted on my sandwich when I noticed a confused guy at the register.  He was asked what size drink he wanted, and then he stared at the cups with a very questionable look on his face.  The cashier was patiently waiting and asked the guy if he wanted a medium size drink.  The guy still looking as clueless as any living human being could, asked the cashier if all the sizes where the same price.  Let’s give this guy the benefit of the doubt for a second.  No let’s not because there were three sizes for him to choose from with each one of them being 10 ounces more than the one bellow it; for example, 20oz, 30oz, 40oz.  Who, in their own mind, would think you could purchase 40oz’s of a product for the same price you could 20oz’s of the same product in the same store? That’s not ignorant that's just F***EN STUPID.  You don’t think so?  Re-read the definitions listed above.  Common sense is something a large part of society is really lacking.  Yes their stupid also lol!