A rare phenomenon that happens when someone pees outside on the coldest of days. The name is derived from the idea that the urine could freeze into an icicle which would resemble a horn. Therefore, that person would be a unicorn down-under or an Australian unicorn.
Bryton: Dude, what's taking so long?
Matt: It froze up on me! Ahh, it's painful!
Bryton: Haha, you're totally an Australian unicorn now!!
Andy: I can relate, that happened to me once too. Ouch!
by shame123 February 12, 2013
The act of a man inserting his penis into a newborn while it’s in the process of being born
Keshawn celebrated the birth of his daughter with an Australian jack in the box.
by Kmandoggiestyle September 16, 2019
The act of inserting objects into ones arse and keeping them in place until a sneeze or other bodily function dislodges it
"Shelly has so many sex toys that I turned her into an Australian PEZ dispenser last night"
by TheDarkSquirrelRises January 13, 2016
When one uses their eyelashes to tickle a woman’s clitoris.

A butterfly kiss but down under.
You see his eyelashes? I’d let him give me an Australian butterfly kiss.
by Kind fellow March 11, 2021
When you're performing cunnilingus on a woman and you blow into pussy lips like a trumpet, causing the lips to flap
Your mother's pussy lips are stretched after all the Australian Motorboats she's gotten
by Ceweal Ceweal with Gwavy February 13, 2018
1. Motorboating but down under and bit to the rear.

2. The act of someone oscillating their face back and forth while pressed against your gooch, while making 'brrrrrrr' sounds.

3. Motorboating for your gooch.
Guy 1: Gee this Coronavirus is really allowing me to find out more about what I like in bed
Guy 2: Oh yeah me too, the wife gave me an Australian Motorboat last night it was nuts
by dinkysweets104 February 9, 2021
When you put your face between her cheeks and motorboat her butthole while shaking your head violently.
I Australian Motorboated her butt until she squealed.
by lordcoppinkaz March 3, 2015