This'll need some explaining to those not familiar with "Sarf London"
A policeman came across a young lad of about 10yrs old loitering around the Dilly (Piccadilly Circus in London. A known haunt of ladies of the night).
The policeman said "Are you on yer own son?". The boy replied "Yeah why?". - "Well you're a bit young to be around here on yer own, what yer doing here anyway?"
"I'm looking for a prostitute" says the boy. The policeman trying not to look shocked said, "And what would you want with a prostitute?"
"Well if I can find a prostitute, I'll "do" her and then I'll catch a dose of the Tilburies. (Tilbury Docks, pox). Do keep up.
"And then I'll go home and "Do" the maid and she'll catch a dose of the Tilburies.
Then my dad will "Do" the maid and he'll catch a dose of the Tilburies. Then he'll "Do" my mum and she'll catch a dose of the Tilburies.
Then my mum will "Do the gardener and he'll catch a dose of the Tilburies,
And I want him to suffer cos that bastard killed my Goldfish.