The word flabbered orginated as AAVE on black twitter in 2017, it means surprised or shook. Though not commonly used anymore its arose on tiktok as a second rebirth.
The act of giving a fellatio laying on a bed/ couch while on your back. Your head is off the side and the male stands over you while his penis is fully inserted down your throat, touching your gag reflex while his testicles are draped and covering your nose and eyes.