found: Work cat.: 99090678: Le Blanc, D.E. Slugging : the commuting alternative for Washington, D.C., 1999:p. 15 (slug lines) p. 22 ("Over time the less-attractive term 'slug' has had many contenders, such as 'instant car pooler,' 'hitchhike commuter,' and 'casual car pooler,' ...")
found: Am. herit. dict.(slug, v.: To wait for or obtain a ride to work by standing at a roadside hoping to be picked up by a driver who needs another passenger to use the HOV lanes of a highway.)
found: Encarta world Eng. dict.(slug n.: a commuter who is not a member of an organized car pool and who hitches rides at established pickup points, hoping for an empty seat)
found: Transportation Research Thesaurus via U.S. Dept. of Transportation Natl. Transportation Library website, Aug. 21, 2005:(casual carpooling, used for: slugging (ridesharing); broader term: carpools)
found: Google search, Aug. 22, 2005(just in time carpooling, informal ridesharing, informal carpooling, instant carpooling, instant ridesharing, dynamic carpooling)