That got me thinking. I wondered if it had anything to do with bo-BOhemian, and blow me down, if I didn't find that it was one of the theories. Here they are, summarised in Wiki "The origin of the term is not confirmed, though there is a plethora of popular theories. Author Todd DePastino has suggested that it may come from the term hoe-boy meaning "farmhand", or a greeting such as Ho, boy!.[2] Bill Bryson suggests in Made in America that it could either come from the railroad greeting, "Ho, beau!" or a syllabic abbreviation of "homeward bound". Others have said that the term comes from the Manhattan intersection of Houston and Bowery, where itinerant people once used to congregate. Still another theory of the term's origins is that it derives from the city of Hoboken, New Jersey, which was a terminus for many railroad lines in the 19th century. The word "hobo" may also be a shortening of the phrase which best describes the early hobo's method of transportation, which was "hopping boxcars", or of the phrase "homeless body" or "homeless bohemian". Additional claims about the word's origin include derivations from the Japanese word houbou 方々, meaning, in reference to travel, "various places", and from the Spanish word jobo, meaning, in the Cuban phrase correr jobos, "truancy". Some Hobos claim it stands for Helping Our Brothers Out."

from wikipedia's hobo page: The origin of the term is not confirmed, though there is a plethora of popular theories. Author Todd DePastino has suggested that it may come from the term hoe-boy meaning "farmhand", or a greeting such as Ho, boy!.[2] Bill Bryson suggests in Made in America that it could either come from the railroad greeting, "Ho, beau!" or a syllabic abbreviation of "homeward bound". Others have said that the term comes from the Manhattan intersection of Houston and Bowery, where itinerant people once used to congregate. Still another theory of the term's origins is that it derives from the city of Hoboken, New Jersey, which was a terminus for many railroad lines in the 19th century. The word "hobo" may also be a shortening of the phrase which best describes the early hobo's method of transportation, which was "hopping boxcars", or of the phrase "homeless body" or "homeless bohemian". Additional claims about the word's origin include derivations from the Japanese word houbou 方々, meaning, in reference to travel, "various places", and from the Spanish word jobo, meaning, in the Cuban phrase correr jobos, "truancy". Some Hobos claim it stands for Helping Our Brothers Out.

hobo 1889, Western Amer.Eng., of unknown origin, perhaps related to early 19c. Eng. dial. hawbuck "lout, clumsy fellow, country bumpkin." Or from ho, boy, a workers' call on late 19c. western U.S. railroads. Hence facetious formation hobohemia "community or life of hobos," 1923 http://dictionary.reference.com/browse/hobo From what I can find, the origin is unknown, though theories have been made. I always thought it came from "Homeward Bound" (abbreviate Ho-Bo) as they constantly move around and I always thought I guess that they were searching for a home.