A board that rationalizes. It has been found that rashboards are pretty useful for scratching rashes.

Can also be used to describe an incredibly stubborn and arrogant person who acts like a smart ass through his/her try hard attempts at rationalizing his/her behavior. People like this can often ruin a good joke by taking it seriously.
Travis stop being such a rashboard you fucking prick.
by 0MNIV0C4TI0N November 27, 2011
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