good job you pointed that out for us Mick.
i just looked it up. here's the definition from the urban dictionary
"A term used to refer to a paedophile. In common usage within correctional facilities. Derived from the analogy that a paedophile, like a rock spider, is always getting into little cracks. Crass and vulgar, I know, but there it is.
"That fucking rock spider had it coming!" (When used as a defence to a charge of murder, where the deceased was a paedophile.)"
better hope zhivvy and basher read your post before they smilingly label everyone in the UK pubs as this , fortunately i