I can only recall the gangster of my generation. 
What I do not know if these descriptions equate the new generation
of gangsters or not :-
a) Young guys n girls moving around in tight-knit groups, hanging
out at
void decks talking loudly (can be Chinese, Malays or
Indians);
b) Conversations that doesn't make sense, peppered with
hokien
profanities or language vulgarities;
c) Swagger when they walk;
d) In crowds, they push their way through without saying 'Excuse
me';
e) They'll always sit on the back of upper decks of buses and tease
female
passengers, especially the young ones;
f) They are boisterous and someone in the group will act crazy or
do
some stunts with supporting laughs from the rest of the group
Which of the above is/are indications of gangsterism? I really
cannot define as unlike gangsters of old, they don't have the nasty
look and tattoos.