Wiki says... Like the very similar term hosehead, the term may have referred to farmers of the Canadian prairies, who would siphon gas from farming vehicles with a hose during the Great Depression of the 1930s.[citation needed] The expression has since been converted to the verb 'to hose' as in to trick, deceive, or steal - for example: "That card-shark sure hosed me." Hosed has an additional meaning of becoming drunk - for example: "Let's go out and get hosed." Another possible origin is derived from hockey slang. Before ice resurfacers, the losing team in a hockey game would have to hose down the rink after a game. Thus the term "hoser" being synonymous with "loser".

A hoser's flannel shirt may also be referred to as a "Kenora dinner jacket". (Some regional variations of this term also exist, usually substituting a hoser-stereotyped local community's name in place of Kenora.)