A necessary component of one's body that allows the user to form logical thoughts and perform actions. Recent studies report that people's sisters are the only known organisms that can live without a brain. Instead, inside their heads are pieces of big chungus's belly fat, which creates the power of stupidity which feeds their damned souls.
Doctor: What are your hobbies?
Stupid sister: NyAAaaAAaAA
Brother: What's wrong with her, Doc?
Doctor: I'm afraid she has no brain at all. I'm sorry. There's nothing we can do.
Brother: What's that like?
Docter: It's like she has autism and down syndrome and times that by 1000.