An ingenious marketing ploy whereby the creators of the dictionary get written definitions from various authors via the web (which then becomes the intellectual property of the creators) who then bind them into a book entitled "Urban Dictionary" and hawk it to various publishing houses until one of them agrees to publish it and make them rich - while the various authors who contributed to the book remain poor.
The creators of the Urban Dictionary are geniuses!
A son's mother - who after he takes a wife, becomes jealous of the wife and considers her competition for the son's affection (which is gross and somewhat incestuous). If not put in her place (told to fuck off) by the daughter-in-law immediately after marrying her son, the mother-in-law will grow fiercely competitive and attempt to wreck the son's marriage by whatever means necessary.
My mother-in-law is jealous of the fact that I married her baby boy and helped him to become a man. What a sick bitch.