The message seems to be that when men are aroused, they tend to throw caution to the wind; or, in the vernacular, when you let your p*nis do your thinking for you, you often make mistakes. Not exactly earth-shattering news, and not really worthy of much study - it’s been a known fact among people of insight for going on four thousand years.
There is a line in "Portnoy's Complaint" where the protagonist, Alexander Portnoy, recites a line he learned from his grandfather or some other older relative. "When the p---- (rhymes with stick) stands up, the brains go in the ground." Which I believe to be true.