Green’s Dictionary of Slang

1. very strong alcohol.

1992		Herman’s Head [Fox-TV] Fill up her tank [i.e. a woman’s stomach] with high-octane [i.e. liquor] [HDAS].
1998–2001		BarMeister 🌐 High Octane = 1 1/2 oz Jack Daniels; 1/2 oz Pepsi.

2. strong caffeinated coffee.

1996

As World Turns [CBS-TV] I’m on my second cup of high-octane [HDAS].