Expressões com a palavra skin

I was wondering what interesting expressions with the word skin I could think of. When I had just started studying english, I remember I got puzzled by the idiom I found in one of Frank Sinatra's songs that goes like "I've got you under my skin". As any beginner student I tried to figure it out literally, but obviously I just could imagine someone living underneath one's skin, which doesn't make any sense at all.

Only after a while I came back to the song and understood what Frank Sinatra really meant by saying that. Imagine him looking at her woman and saying: I've got you under my skin. As I said previously, it's impossible to picture her living literally under his skin, but can you think of what could be attached to him in such permanent way? Yes, tattoos. They're a good way to understand the idiom. Just like tattoos, which is indelibly lodged with you, if you've got a girl under your skin, you can't get unattached to her because you keep thinking about her, you're very attracted to her, she's almost a part of your body, and you became very dependent of her love. So, when Frank Sinatra said that to her babe, he was trying to say he was falling head over heels for her, very in love with her.

There's a very similar idiom to "to have someone's under your skin" but whose meaning is the complete opposite. If having someone's under your skin means you're very attracted to someone, if somebody gets under your skin, it means they can really annoy you. As you can see, there's nothing lovable or sweet about that idiom. Suppose for example you hate your boss because he's always looking over your shoulder. You could say: My boss really gets under my skin. If I was asked about what really gets under my skin I would remember of those times when someone is standing behind us looking at our computer screen. I think that's really annoying and I'm not the only one thinking that way.

That's it for today guys. I'll be back with some other bunch of idioms soon. Keep tuned!