I didn't do the translation, but I think there's a pun here. Pretty sure she's saying "It's cool" as in awesome, but her shirt says "cool" as in the weather. I'm guessing she's meant to be a bit of an airhead? This would be kind of like walking about with a shirt that just says "It's cold!". I'm not witty enough to provide an equivalent pun, so I didn't update it. Edit: Lessened the definitiveness of my statement.
I didn't do the translation, but I think there's a pun here. Pretty sure she's saying "It's cool" as in awesome, but her shirt says "cool" as in the weather. I'm guessing she's meant to be a bit of an airhead? This would be kind of like walking about with a shirt that just says "It's cold!". I'm not witty enough to provide an equivalent pun, so I didn't update it. Edit: Lessened the definitiveness of my statement.
Looks like she got a shirt that says "It's cool!" in Japanese but didn't realize it's a different sort of "cool".
It's a classic gaijin trope. 怪しい日本語Tシャツ in the commentary title makes it unambiguous since that's what the trope is called (along with 面白い日本語Tシャツ).
