Reply #5: A different sourcing, courtesy of William Safire of the NY Times [View All]

The meaning of this distinctive American verbal phrase goes beyond “reject” or “dissociate from” to a more vividly figurative expression of “to damage a reputation; to use as a scapegoat.” For its origin, I turn to our leading popular slanguist, Paul Dickson, author of “Slang —the Topical Dictionary of Americanisms,” just deliciously updated. Origin?

He says he believes it to be back-formed from a baseball team’s clubhouse man, who called for the ballplayers to board the team bus with “Bus leaving. Be on it or under it.” The slanguicographer backs this up with a citation from a 1980 Washington Post article and offers another usage that extends beyond sports: the rocker Cyndi Lauper in 1984 was quoted as saying: “In the rock ’n’ roll business you are either on the bus or under it. Playing ‘Feelings’ with Eddie and the Condos in a buffet bar in Butte is under the bus.” <[/div>

http://www.nytimes.com/2006/11/19/magazine/19wwln_safire.html?ei=5088&en=a21ab07af4bda93e&ex=1321592400&adxnnl=1&partner=rssnyt&emc=rss&adxnnlx=1189915543-dVa8TixsbB8aPgkeWzHtHg