Green’s Dictionary of Slang

(Aus. teen) an extreme emotional reaction, pleasurable or otherwise.

1947

Argus (Melbourne) 15 Nov. 7/1-2: ‘I nearly had sooperhootics when I received the invite’ [...] Further inquiry revealed that ‘I nearly had sooperhootics’ is a euphemism. It was condescendingly explained to me that this is an indication of extreme surprise.