"Jobbing" is the insider term used in pro wrestling for losing a match. A jobber is a wrestler who generally loses all of the time. In the old days of the wrestling territories, and even today to some extent, wrestlers are jobbed out, meaning that they've lost so many time that the fans will no longer accept them as viable opponents. A jobber is also called a jabroni, which is carney talk for a loser.

Job"bing (?), a.

1.

Doing chance work or add jobs; as, a jobbing carpenter.

2.

Using opportunities of public service for private gain; as, a jobbing politician.

London Sat. Rev.

Jobbing house, a mercantile establishment which buys from importers, wholesalers or manufacturers, and sells to retailers. [U.S.]

© Webster 1913.