Hairs are showing.

[tufguy]

"A lot of hairs are coming out of you hat."

"Your leg hairs are showing."

"Look at all these hairs on your hands."

We say "your hair looks nice, have you had it cut" but can hair be plural as well?

Please check.

[ChinaDan]

Yes. We can refer ti individual hair follicles (countable) and so say "hairs", or we can refer to all of it (uncountable) and so say "hair".

Hence the joke:

Tom: "I got a hair[ ]cut today".
Bob: "Yeah, which one?"

[emsr2d2]

"A lot of hairs are coming out of your hat."

Note your typo in post #1.

However, even with that correction, it's not very natural. They're not "coming out of your hat". They're probably visible under your hat. That suggests that although most of the person's hair is covered by the hat, there are quite a lot of hairs escaping!

[Rover_KE]

"Your leg hairs are showing."

"Look at all these hairs on your hands."

Depending on the context, it could be inappropriate/indelicate/mortifying/rude to draw attention to what the listener may consider embarrassing afflictions.