YOU SAID:
Yeah, I'm a gamer. How could you tell?
INTO JAPANESE
俺はゲーマーだどうしてわかるの?
BACK INTO ENGLISH
I'm a gamer. How do you know that?
INTO JAPANESE
私はゲーマーです。どうしてわかるの?
BACK INTO ENGLISH
I'm a gamer. How do you know that?
You've done this before, haven't you.