What is No Brainer?
1.
A dumb question or response. Something one shouldn't even have to think about it.
Dude1: Hey, man, where's the basement?
Dude2: Try downstairs, bright spark!
Girl: Whales are... big.
2.
could be used as in "definetly" or "of course"
Jim: Do you have to put your marshmallow in the fire?
Clark: Dude, it's a no brainer, as a rule of thumb campers should put their marshmallow in the fire.
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3.
Not needing a brain to operate task in question
Hey, working a till in Macdonalds is a no brainer which is just as well as chavs need the work
4.
A person of either the male or female persuasion who absolutely refuses to participate in oral sex.
'Man, I had to leave that girl alone. The p***y was good, but I found out she's a no brainer-she wouldn't give me any head!"
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