goat

An incredibly overused term thats short for "Greatest Of All Time", mostly used by people below 20 (at the time of writing) that don't really have the experience to make such a claim. A funny meme or good joke or nice sandwich is enough to get the "Greatest Of All Time" label because most people using this term are young and simply unaware of actual "GOAT" things.

Some people even go the extra step of using the wrong grammar, as if they are talking about goats the animal, because why not (see second example)

"My favorite streamer is the goat" (okay usage)
"My favorite streamer is such a goat" (not okay)