How do you say 'quitter' in Korean?

In a post I made about a month ago, I talked about my journey learning Korean with the help of Duolingo. All of this is because of my love for the language.

After a two-week streak learning the language, along the line, I ended up with an emotional breakdown, and the urge to be on my phone was like twenty percent out of a hundred. This made my activity on everything slow down, and three days ago, when I managed to pull myself together, I decided to check my email.

To my surprise, Duolingo had sent me tons of emails reminding me of how bad I was falling behind. I mean, just a few days of being away and they were already on my neck, almost squeezing the life out of me.

The email that cracked me up the most was this one.

I'm like how do you guys come up with such dark humor all in the name of reminding someone to pick up the pace? I mean, I was laughing yet shit was hurting. They didn't even teach me how to say 'quitter,' yet here they are asking me the question and faking an apology in return. I could have taken offense, but you know, it is what it is. I literally signed up for it when I told them I was in for a thirty-day streak. Lmfao.

^{here's me asking "what do you mean b#tch?"}

Anyway, to avoid such dark insults from coming my way again, I had to visit the app. I was expecting more dark humor, but luckily, they welcomed me back with all the warmth I could ever ask for. Lol. It's been fun practicing though, and I kinda love the way they remind me of my lessons; humorous, dark, and a little annoying.