phr. Meaning, "that's a good idea!" or "I'm cool with that!"
The origins come from the idea that your brain is made up of cogs, and the smoke generated from the cogs' hard work makes smoke, or "fumes" that get you high.
Tammy: Let's go get a snack from the vending machine.
Lori: Yo, gettin' high off the fumes. I haven't eaten anything today.