Keithish is a language where a fruityperson lets their emotions spill out through keyboard spam usually through excitement, love, or any other strong positive emotion.
(Thank you Peach for being able to define this word !!)
Mog: Oh wow, look at Steven go.
Steven: DJSUIEGRJ&$@T$Y^#&%UT@I%UY#&%T^$^)$()&@^%$@#UYUAWUE
Lemon: Dang.....they must be speaking Keithish!!