A person easily distinguished by his "special" characteristics. A beaner often looks like or resenbles a mexican or person of hispanic decent. A beaner also usually has a way of putting himself in uncomfortable situations. A beaner shows no signs of emotion under pressure. Also a beaner sucks with girls. To "pull a beaner" consists of getting in a situation where you could "get some" and act like an idiot and ruin it, most likely by not talking to the girl at all and ruining any possibilities that could come out of the situation.
Oh my god! Don't be a beaner!
Get over there and talk to that girl! Don't go and pull a beaner like you did last time!