What should I wear for a first meeting in karaoke?

So I met this guy in a formal event around a week ago, we started to talk and became friends. We were talking about music, singing and stuff like that. He suddenly offered to take me to a karaoke. It's not like a party or anything, it'll just be the two of us. I'll stick to something casual but I'm not sure about what to wear. So What do you think i should wear? PS It's very hot since it's summer.

What should I wear for a first meeting in karaoke?
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