Is it normal stewpid people annoye me?

Yes, that was completely intentional so no need to freak out and turn into a grammar nazi.

I can't stand people who lack common sense. I work at a retail store and the other day, this man came up to me who I seriously thought was a troll.

He came up to my register and put down a model solar system in a box. He looked at it and said "wow, they must really love the Sun, they made it look huge on this". I laughed at him thinking he was joking and I then said "ha, that's a good one" and he shot back, "What's a good one?" with a DEAD SERIOUS face. I said "well, why wouldn't they make the Sun that big? That's not even large enough to actually be the Sun". He then said something like, "That'd be pretty scary if the Sun was larger than Earth my dear as we'd probably burn up" and I just shook my head, he paid for his item and he walked away.