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6.
A Brainer is when you do something because it had to be done and you knew it was the right thing to do.
Brainer
1.You gave that guy some of your bone marrow well that's a brainer.
by WolfBrother13le April 24, 2013
 
1.
a girl who sucks dick (gives brains)
that nasty hoe is a brainer too
by Mandy October 10, 2004
 
2.
Slang for someone who gives oral sex
"Yo you know Shayna's a brainer right?"
"Word?"
"Ye man; go chop dat"
by TheCurryFairy September 07, 2006
 
3.
An easy decision made using the brain. As opposed to a 'no brainer', an incorrect term seeing as how all decisions are made using the brain, as pointed out by SourceFed's brilliant Joe Bereta.
"I could save that man's life with a simple marrow donation, it was a brainer."
by anIrishViking April 24, 2013
 
4.
The satisfaction you get when learning something you didn't know before or to share something else with someone who didn't know about it before. Like a boner, but with your brain.
Mary: John must be the most common name in the world.

John: No, Muhammad is the most common name ever.

Mary: Oh. I didn't know that.

Tommy: Total brainer.
by Three years later July 14, 2010
 
5.
The act of using your brain to make a decision.
It was a brainer to watch SourceFed.
by Not Joe Bereta April 24, 2013
 
7.
When you think about a decision and make the right choice. Like a no-brainer but better.
The decision was a brainer
by Sourcefed fan15 April 24, 2013