In
standard Japanese, yarou means
bastard,
son of a bitch, and
asshole.
Commonly used in the phrase "baka yarou" = stupid bastard.
Also, phrase made famous by Antonio Inoki is "Nanda kono yarou!" = loosely translated as "what the fuck, you bastard". As a matter of fact, on my first trip to Osaka to see my friends from college, I bought an Antonio Inoki t-shirt at America-mura in Shinsaibashi with this written on it. I have since lost that shirt though. :(
However, in the
kansai dialect,
yarou has the same meaning as
darou in the
tokyo dialect = isn't it? aren't you?. Thus, it can be sometimes confused. When used as a
tsukkomi after someone does or says something
stupid,
aho yarou means "you are stupid, aren't you.