A girl from Southampton or the surrounding area, under the legal drinking age who puts it about to get drinks brought for her/entry to over 18's clubs etc
"Have you seen those sloshbags all over Bury Tomorrow"
"That sloshbag is going to be hanging in school tomorrow"
"Look at the Tatty Bo Jangles on that sloshbag over there!"
"That Sloshbag over there wants me to go home with her, but I don't want to do the walk of shame when she has to go off to school, maybe her dad could give me a lift or something?"