Green’s Dictionary of Slang

1. anilingus.

1979		Maledicta III:2 218: Australian = anilinctus practitioner (rimming from Down Under).
2015		‘Chelsea G. Summers’ in Vice 10 June 🌐 I can sense in anilingus terms as disparate as Australian (you are going down under, after all), rosie (after ‘rosebud’), lickety-split (self-explanatory), and tell a French joke (ditto).

2. an anilinguist.

1989–2003

R.O. Scott Gay Sl. Dict. 🌐 Australian sex: To start one partner licks the back of the neck and shoulders of his lover, then lifts his tongue and moves it a tiny bit down the spine. Then he slowly works his way back up the spine to lick the back of the neck and shoulders, perhaps moving around to the side or front to lick the side of the neck or kiss the mouth. He then lifts his tongue and places it a tiny bit further down the spine than the last time. You take 15 to 60 minutes to work your way down to the anus and beyond. That’s the Australian part. From there, this often leads to rimming and screwing.