Have you ever watched a basketball game? A "jump off" or "jump ball" is when a member of each team faces one another in the middle of teh court. The referee then throws a ball up in the air and the team members have to jump up to get it, first one that gets it gets the ball. The is used to start the game, and resume play in certain situations.

It depends if the sportscaster was talking about the game or a female. In the instance of a female, a jumpoff is considered to be a groupie or women that typically seek out high paid athletes for sex. There hope is to become a steady girlfriend or future wife but the relationship doesn't go further than sex. Example: Friend one - "Are Charles and Christina dating? I saw them go to the hotel last night." Friend two - "No girl, Christina is just a jumpoff. Charles' fiancee is out of town for the week."

Joseph Rios answer is correct. However, jumpoff does have another meaning, so watch out! Never refer to a person (especially a girl) as a jumpoff. Unlike the defintion Joseph Rios gave, you are not saying that the person is "exclusive" or "hot". In this context, a jumpoff is a person who is either a casual sex partner (friends-with-benefits) or a person who is promiscous.

a jumpoff is something exclusive, anything that's hot,brand new or something everyone wants.