Peculiar to Liverpool, England. Ancient in origin, corruption of English with Gaelic normally follows. Arrll generally considered to represent auld, Gaelic for old. Means an old trick, but more specifically used throughout the socio-demographic strata to describe someone who is sly. Example: Yous did a really arrll-arse trick yesterday.
ARRLL-ARSE
Meaning of ARRLL-ARSE in English
Slang English vocab. Английский сленговый словарь. 2012