League of Legends has a simple vocabulary for praise and abuse. “That” before something means “is very good or inherently overpowered.” “This” before something means “is very bad or inherently useless.” You’re in the middle of a game and don’t have time to type a lot of invective, but the most important thing in the world is making sure other people know you are better than them at online games, so you can quickly insult your teammates with “this cait” to make sure everyone knows that your team is only losing because Caitlyn is not performing up to your expectations. Make sure to put it in all chat so the other team can share your scorn for your teammates. Alternately, if “this cait” is on the other team, this will let them know that their team is bad and they should feel bad. Because that is the kind of community the game still supports, even after things have improved.
This also technically gets around using profanity and verbal abuse, although Tribunal reviewers (and most other players) will recognize that people who use a lot of “this cait” will also throw out streams of profanity and racial slurs.
“that cait” is usually reserved for opponents, rather than praising teammates, again to emphasize that losing is not your fault. Ashe, of course, gets it more frequently on either team because of the meme.