An erection that some men get when proposing marriage to the love their life. It should be understood that boners are complex events that can arise due to a combination of fear and anxiety as well as sexual excitment, and the act of proposing often involves all of these. So if a guy gets an engagement boner, it doesn’t necessarily mean he wants to hop into bed then and there. And if he doesn’t get an engagement boner, it simply means he is totally normal and he could still be wildly turned on by his partner. (In chosing a life partner, women should focus more on what kind of man he is, and how reliable, honest and hard working he is than whether he gets a boner when he’s down on one knee.)