[tailspin2019]

Maybe derived from “a line”?

[nexton]

As an Aussie, I assumed it was a reference to: https://en.wikipedia.org/wiki/Allan_Border

[andrewshadura]

My understanding it's a reference to Steve Coogan, who played Alan Partridge, who in one episode sees a friend called Dan, and starts shouting his name, but Dan doesn't react. Alan proceeds shouting: Dan! Dan! DAN! and eventually gives up. This scene was later parodied in a BBC programme about animals, where one animal shouts Alan! Alan! ALAN! and then realises the name's wrong: STEVE!