The guards
The Gardaí, the Irish police. Nobody says Garda Síochána out loud if they can help it.
Turn down dat music or de neighbours'll have de guards called.

Shall I translate it into posh English for you, boss?
Well, hello. Fancy meeting you here. Here it is in posh English.
Lower the volume of that music, or the neighbours will summon the constabulary.
Questions
What does the guards mean in Ireland?
The Gardaí, the Irish police. Nobody says Garda Síochána out loud if they can help it.
How do you use the guards in a sentence?
“Turn down dat music or de neighbours'll have de guards called.”
Updated
On the list: Irish slang words