Originates from Chicago, specifically the Italian population. Some believed the mafia coined the term. Its commonly confused to mean a combination of Jag-Off and Homo.
Definition: Jack ass mother fucker.
Used a lot in road rage due to the piss poor driving in Chicago. Jagmo is almost always follows the word fucking.
Any object that when inserted into the mouth brings oral pleasure; excitement of the taste buds. Also commonly referred to as a "schmook." A jagoop could be anything from chewing tobacco to "schmookie good" food.
Let's go watch some football and get a big ole jagoop.