Korean Kids Don't Understand Sarcasm

I think Korean kids are rather sheltered. They spend so much time in school and in after school academies that a lot of them lack social skills and a sense of humor. Yesterday was the level-up test, which obviously decides if they advance to the next level at my school. Partly to try to get them to relax a bit, and partly for my own amusement, I was on a roll with the sarcasm, but nobody seemed to get it.

The names have been changed to protect the oblivious.

Teacher James: "Tom, please clear your desk."
Only Kid In The Class Named Tom: "Me?"
TJ: "No, the other Tom."
Only Kid In The Class Named Tom: *Blank stare*

TJ: "Use your marker to fill out the test sheet."
Sally: *Holds up only marker on her desk* "This?"
TJ: "No, your other marker."
Sally: *Holds up pen* "This?"
TJ: "That's not a marker."
Sally: *Blank stare*

Billy: "Teacher, can we write in pencil?"
TJ: "I don't care. You can write in your own blood if you want to."
Billy: "So we can write in pencil?"

With 45 minutes remaining in the class

Alice: "Teacher, how long is the next test?"
TJ: "An hour and a half."
Class: "AAAAARRRRRRRRGGGGGGGHHHHHHH"

Joe: "Teacher, Monica stole my bag."
TJ: "Wait, do you hear that? . . . That's the sound of me not caring."
Joe: "OK."