Are any of these examples of gaol slang entering normal slang or at least youth jargon?
'Siema' is a trademark word of en.wikipedia.org/wiki/Jerzy_Owsiak
The others are used by older people who think they sound cool and young when they use it, or by youths who think using slangy words will make them cool. I think 'spoko' is entering more common speech. Sometimes I use it, but never in formal situations. I guess these words sound a bit... ridiculous. I'm 22, so I guess I'm still a youth, but if someone started talking to me like that, I wouldn't treat the person seriously.
Only Jurek Owsiak can say 'Siema!' and not turn out silly. :)