Dag is an Australian and New Zealand slang term, also daggy (adjective). In Australia, it is often used as an affectionate insult for someone who is, or is perceived to be, unfashionable, lacking self-consciousness about their appearance and/or with poor social skills yet affable and amusing.
It is also used to describe an amusing, quirky and likeable person (as in, "He's a bit of a dag") and is non-pejorative. The term was more widely used in the 1970s due to the popular New Zealand comedy of Fred Dagg (John Clarke). The term may be simply affectionate, such as when it was used to describe the...