This terms refers to a bunch of non-sensical talk or when someone keeps talking a bunch of bullshit. I first heard it when I moved to Philly, but don't know the exact origination.
Man, she was talking all that fly shit the other day, but I wasn't payin chic no mind.
1. A small fly with triangular wings that crawls out of drains in the bathroom and breeds in septic systems.
2. A greenbottle fly of the kind that frequents fecal deposits.
An American insect species uniquely equipped to identify dishonesty, corruption and politically deranged individuals at THE MOST opportunistic time, exploiting and exposing their underlying derisive motivations.
Hey, did you watch the Pence/Harris debate last nite?
Yeah. But all I can remember is when Pence had that thing land on his head.
That was a Shit-Head fly, and it was just doing its job.