Green’s Dictionary of Slang

(Aus./N.Z.) very angry, furious.

1984		Partridge DSUE (8th edn) 1044/2: since ca. 1945.
1985		‘Thommo’ Dict. Aus. Swearing & Sex Sayings 114: SHAT OFF — Disappointed, frustrated, let down, same as shitted off or pissed off.
1999		‘IMM Archive’ at themusic.com.au 20 July 🌐 But what troubles me the most about the Internet is when someone sends you some long screed asking for the world of information [...] [a]nd they get shat off when you reply with ‘Pass, thanks.’.
2002		‘Ian’ at Alcoholics Anonymous 🌐 But I was thoroughly shat off because I had not received my promised ‘spiritual awakening as a result of doing these steps’ as it clearly states in Step 12.
2003		McGill Reed Dict. of N.Z. Sl. 184: shat/shat off Angry or depressed. ANZ c1945.