Wiktionary
arse over tit
adv. (context AU NZ British idiomatic vulgar English) tumbling; falling; upside-down; unstable or unbalanced.
Usage examples of "arse over tit".
I've left my run too late and I'm just about ready when I'm knocked arse over tit in the toilet as the Pan Am jet makes a steep spiralling descent over Tan Son Nhut airfield, so as to be less exposed to any enemy fire aimed at it from the nearby swamplands.
Ben didn't like moccasins himself - they always became too floppy, sending him arse over tit at inappropriate moments.
It's when Lucia turns, nearly falling arse over tit in the process, and finds herself staring at the absurdly huge shape which is even now bearing down on her.
They don't notice the old bloke until he goes arse over tit into the water.