
somebody doesn't know about the fear-boner, or the random boner, or the awkward boner, or priapism, or tachycardia (yes, that can trigger it), or high blood pressure, or erectile dysfunction...
really, anybody who gets average sex-ed knows about this. besides, the wang is about as unpredictable as a d20. there's a reason viagra is so commonly prescribed.
tl;dr: the person in red clearly doesn't understand how it works.