Rockstar: This is the answer.
Me: (annoyed, because I told him before) You can’t do that. If the first digit is smaller than the second in subtraction you can’t just –
Rockstar: What are you talking about?
Me: Oh. Sorry. You didn’t do that.
Me: Hold it. You don’t get to be smug yet. I’m still checking.
Rockstar: <Barely suppressed snort>
Me: Y-eah. Your answer is right. You can be smug now.
Rockstar: <SNORT> <SNORT>
Rockstar: 60+10=70. That is so pathetic.
(I look at him in surprise)
Rockstar: <hurriedly> Easy! I just mean easy.
Still awhile later…
Me: That really is wrong. You just lost your smug card.
Rockstar: Who farted?
Me: Nothing stinks. Do your work.
Rockstar: HAR HAR HAR.