YS dully white

[Saila]

any ideas what this means?

a group of 7 young lads just walked down the middle of our road, all wearing jumpers with 'ys dully white' on the back

seemed nice and smiley, harmless group of lads. - just wondered what it was/meant?

edit:

just found out it stands for White Dulwich Gang based in kingswood estate, dulwich - nice

i wish they'd stay in dulwich and stop lowering the tone of peckham.. tut tut