realcastic
noun: When a person attempts to be sarcastic, but the other person believes their words to be serious.
a: OMG I weigh 115, I'm an effing elephant!
b: Yes we might as well call you Dumbo and give you wings.
a: What do you mean?
b: Chillax! Don't be realcastic.
b: Yes we might as well call you Dumbo and give you wings.
a: What do you mean?
b: Chillax! Don't be realcastic.