Pooners (the irl people): TIFs, especially those that don't pass well or are barely trying. "poon" meaning "vagina" (that thing only women have). Not a slur, but sometimes seen as one by other queers given that it recognizes that transmen aren't men.
Pooners (the drawings): A horrifyingly cute depiction of TIFs by TIFs. The prototypical pooner has pink, flushed skin, feminine lips & hips, various forms of visible self-harm (scars, ear gauges, nose rings, degloved arms for phalloplasty, zippertits), and either a bulge from a packer/rotdog or cameltoe. Even pooners comment on how scarily accurate the art is compared to the real deal.