An unintentional orgasm without any real stimulation so it's all in your mind.
"Oh emm gee. I totally just had a brain gasm while laying down infront of the fan watching t.v."
n. An intense rush of intellectual fervor or excitement in response to a stimulus such as recognizing a literary allusion in "The Simpsons" or finally understanding how to do that advanced calculus problem or even just anything really cool. Usually accompanied by inability to formulate actual words and an intense enthusiasm about the subject that induced the braingasm.
That geek had the biggest braingasm after she saw LotR:RotK.
An orgasm of the brain, something that would be the equivalent of information sex, something that would make a nerd smile in a kind of creepy, happy way.
Nerd 1: Dude, we just got our new Calculus books!
Nerd 2: Alright! Braingasm!
Nerd 1: Yeah, we're so cool
When you find out some unknown piece of information, and you feel a rush of Intellectual glee. Related to intellectual masturbation, and Brain Jizzing
When Brian read the theory on equilibrium, he had a Braingasm
The sudden, and often timely, understanding of a subject, usually in school. Most commonly paired with a loud exclamation of "OHHHHHHHHHHH! I GET IT NOW!" or something very similar. Usually done by the less studious members of the class, who understand it right before a test or quiz.
Teacher: So if you want to make x=2, you can. Just plug in 0 for y.
Student 1: OHHH! OH! OH! I GET IT NOW! So you just have to ...?
Teacher: Yes, Michelle, that's it. I've explained it for 3 weeks now."
Student 1: SWEET! I WILL SO ACE THIS QUIZ!
Student 2: Someone just had a braingasm...
the action of seeing or hearing something so awesome that you grunt like a rutting bull.
I was listening to dubstep the other day and the bass drop was so filthy that I had a brain gasm! ARRRRUGH!!!!
the pleasant, clearing, "orgasm-like" feeling your head and sinuses experience after a hearty sneeze.
I had a braingasm when I sneezed.
When your brain finally figures out something that was on the tip of your tongue (i.e. an eighties song or the name of a movie, etc.) and you end up yelling it at a random moment after the fact that is at a point of time that has nothing to do with the thing that you remembered !!
("OH My GOD !!!, Just had a Braingasm!!!!!!")