Originated from the word Hoser describing a stereotypical Canadian Hockey player. Has recently turned into a derogatory term describing slutty women completely deviating from its original meaning.
"History: The term originates from a syndicated television comedy about a fictional television station: 'Second City Television Station' or 'SCTV.' Comedy skits on the show were presented as actual programs. One such skit was a program entitled "the Great White North" - the hosts, comedians Rick Moranis and Dave Thomas (portraying Bob and Doug MacKenzie), embellished and exaggerated the stereotypical American image of how Canadians talk and act. The characters (Bob and Doug) drank beer, while bantering back and forth, inflecting their speech heavily with 'eh?' and the occasional 'hoser.' "
Urban Dictionary - hoser