When you're shifting(
french kissing) a right beure (
good looking girl) and you put your hands down her leggings/skirt and
underwear and grab her ass (hence why it's called bare arse you grab her bare arse) used in Ireland mainly in the west i.e. Galway, Mayo
Friend: That girl you were with in town didya get with her?
Lad: Sham it was
more than that I slipped my hand down her
knickers and I got to bare arse her
Friend: Seriously she's such a feek
you're a lucky prick
Lad: Shup ya dirty fridget