A condition in which part of your brain tissue is displaced and then bulges out. This state occurs due to the absorption of too much information memorized for an exam and forgotten immediately after taking said exam. Usually take place during college finals. Condition should be taken seriously and is best assuaged by watching television, eating junk food, or in case of emergencies, mindlessly staring at a blank wall.
First guy: "Man, I totally got a mental hernia from memorizing all that BS for my exams."
Second guy: "No worries, just stare at that wall."