A temporary feeling of retardation that occurs while studying for a promotional process where a plethora of some useful, mostly useless, contradicting BS, is the subject matter.
Rookie: Sir, can we go over fire behavior today?

FF: dafuq is that shit?

Officer to rookie: Stay away from him, he's got mashed potato brains.
by A sad FF April 22, 2017
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That feeling of mental retardation after coming down from a long night of tripping on acid
Man, I caught some major mashed potato brains the last time we tripped. I don't think I could deal with that again.
by hobolizardg January 4, 2012
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