A guy called me sushi?

So, I have a crush on a co-worker and I've been wondering if it's mutual because although he hasn't made a move we do joke around a lot and I've already felt that he always finds excuses to talk to me. So, I speak Korean and he knows it and everytime he sees me he says hello in Japanese (he does know it's not the same thing) but today he called me sushi and when I looked he was like "why did you look?" and asked me how I was doing. Why did he call me that?
A guy called me sushi?
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