An erection that is ordered, mandated and/or required during the time when a couple is trying get pregnant. This is most often needed when a couple is having sex purely for the purpose of getting pregnant, whether they are in the mood for sex or not.
Husband: "My wife just texted me that I need to get home and bang her."
Friend: "What? Your wife texts you for sex?"
Husband: "Nope. She's ovulating. Gotta go put on my game dick."