A person who dosen't understand sarcasm in any way. They are always being realistic in such a way that it is annoying.
*people are looking at moss*
Person 1: I went to the Jay-Z concert!
Person 2: Yeah, and I'm Jesus.
Person 3: No you're not! Jesus lived so long ago! If you were Jesus, you would be In heaven right now, and I know that you will never get there!
Person 2: Wow. You are such a realistico. I was beng sarcastic.
Person 3: What's Sarcastic?
Also see:Smart Aleck realistic sarcasm