Slider
An ice cream wafer: a block of ice cream between two wafers.
Heard in Down
Grab us a slider from the van, wee man, and get one for yerself.

Shall I translate it into posh English for you, mucker?
How the devil are you? Here it is in posh English.
Do fetch me an ice cream wafer from the van, young man, and purchase one for yourself.
Questions
What does slider mean in Ireland?
An ice cream wafer: a block of ice cream between two wafers.
Where in Ireland do people say slider?
People say slider in Down.
How do you use slider in a sentence?
“Grab us a slider from the van, wee man, and get one for yerself.”
Updated
Same phrase, other counties
- Down (not in the dictionary)