A "hoser" is an irresponsible, not very smart, unemployed young man who lives primarily to consume junk food and beer, find idle amusement, and avoid work (the GREAT EVIL!). It's actually a euphemism for "fucker", and is a term that hosers use for other hosers. Used between friends it is a friendly form of joshing to call the other a "hoser", unless you say it with some venom in your voice, in which case it isn't so friendly.