A swill is very similar to a chav or a townie, infact i think think they are the same thing. Any way a swill is a person that usually listens to really bad music like chart crap and rap. Girl swills tend to be very tarty,wear lots of burberry von dutch and any other thing thats supposed to be fashionable and cheap looking and wear lots of "bling" fake gold jewellery. They also tend to scrap all their hair back and tie it up on the top of their heads and they wear make up thats looks like it's been applied with a shovel. Boy swills tend to be very stupid. They like to wear track suits and like nike. They also like bling and wear baseball caps so the the top bit sticks right up in the air making them look like dickheads. They also like burberry.
Go watch vicky pollard on little britain and you will find out.