A large, oversized spliff, usually made with weed rather than cannabis resin.
"Let's stay at home and smoke a Fatty Boom-Batty"
A cannabis joint of unruley size. Usually pertaining to a double papered joint that while of regular length has a disproportionately wide girth.
Yo, I just rolled up a fatty boom-batty jay of this skunky ass weed yo! Were gonna get so high...yeah!