To Brain Train someone is to "school" them, or "shut them down" with
a direct factual comment, sometimes with
the help of sarcasm, (but not always) that
renders them speechless.
Dude 1 Says: I think my rotor's need replaced because everytime i start my car it squeals.
Dude 2 Says: (with sarcasm) Yeah...Because that wouldn't be your
belts needing replaced.
Dude 3 Says: He just totally Brain Trained