That's Gnome

Kuitar's SexyBeard emote cropped onto a gnome.

The phrase "that's gnome" is used in the Jak speedrunning community to inform newer members that something they discovered is already known.

First instance of the phrase being used.

The term was first used by Ruh on July 12, 2018.

History
Community Jokes	That's Gnome • Surprise.mp4
Hieroglyphics	Da Bleeblay • The Elder Scroll