The same thing you wear when its 75 F? Idk man, they're just numbers. You can project whatever you want onto them.

what am I supposed to wear outside when it's 23 degrees?

Shorts, T-shirt and flip-flops, or

Short sleeve shirt (Hawaii style), linen trousers, moccasins.

Something along those lines would be good at 23^o^ C.

As a lifelong celcius user I have a very intuitive sense of how 23 degrees celcius feels. I have no intuitive sense of how 50 degrees Fahrenheit feels.

If you're used to a system then it's intuitive.

30 is hot, 20 is nice, 10 is chilly, and 0 is ice

Picked it up from a guy who teaches Latin on YouTube of all places

0°C means that weather starts to be icy and you need to be careful when driving.

20°C is mild warm. 30°C is hot. 100°C is sauna.