a louser (think houser but with a L) is someone who spends free time doing fuck all. this someone or someones could be doing Something, but that something is actually a meangless waste of time. the someone in question, has no life, no hobbies that matter and is hardly ever productive. lousers may think they help, just by being in the room, but in fact they do not.
nana what are you doing?
playing free cell.
tata what are you doing?
jeez! you guys are fucking lousers!