"Sham" is the Irish term for the British term "chav".
A sham is characterised by attire such as tracksuits (the whiter the better), baseball caps on very back of head, hooded jumpers (with hood worn on head), tops with horizontal stripes, Ben Sherman & Burberry articles, tight haircuts, plenty of big jewellery (especially gold), excessive rings on fingers, tatoos on hands, lack of intelligence, unemployment, incomprehendable accents, drug/alcohol abuse, antisocial behaviour, casual violence, incest, rape, petty theft and general crime.
"Sham / Chav culture" is growing quickly in the UK / IRL.
Term used by shams to refer to one another, similar to the way the token young black male calls others "nigga".
Basically the scum of the scum.
"Man, you look a right sham chav with that cap on your head"