Green’s Dictionary of Slang

1. (US black) a bad scare, a serious fright [? jabooby n. (marijuana), among the effects of which can be temporary paranoia; however a simpler ety. would be the trad. cry of boo! in order to scare someone].

1994

C. Major Juba to Jive 53: Boo n. (1930s–1950s) a bad scare; corruption of ‘jabooby’ (marijuana) so called because it sometimes induced anxiety or fear in the user — what is meant by a ‘bad experience’.

2. a ghostwriter [pun on SE boo! + ghost(-writer)].

1979

J. Homer Jargon 102: Some of the most renowned journalists [...] have [...] earned money (but not credit) as boos [HDAS].