A Norman is a sexual term for sleeping with your protege, son, mentee, or sidekick's girlfriend and knocking her up. This is the exact opposite of being cuckolded.
The term comes from the American Comic Book character Norman Osborn, who has banged hot young chicks right under the noses of his son andand proceeded to get them pregnant.
It is considered in some circles that making her pregnant is really only a "half" Norman, and to do a full Norman, you have toss her off a Bridge.
Oh man, dude totally Normaned his son. You should seen the look on his face when he found out his pops was hitting that shit all along and he's been raising his brother all these years.