Probably just that we have certain style aspects in common, and he's cute. I may admire certain tattoos or be curious about them if I get a good look at them.
He hasn't said a word to me, but has he made eye contact or even noticed me? If so, does he smile when he makes eye contact with me [or if no eye contact with me, does he smile when locking eyes with others]? Does he have an open expression/body language/seem friendly, or seem stoic and closed off/unapproachable?
If he acknowledges people around him in an open and friendly manner [even if it's not directed at me], I'd be much more likely to approach him and strike up some kind of conversation. I think he's probably at very least, a guy who is self-aware and mindful of his surroundings/people in his presence, probably polite, and those are qualities I appreciate in people I intend/desire to spend any real amount of time around.
Sounds like a punk rocker maybe or someone into rock music. I probably wouldn't think too much of him, not in a bad way but I don't really think a lot about random people. He doesn't sound like he'd be my type though but if he's great looking, I might think "he's cute for a punk rocker/emo/etc"
Badass! Lol. He doesn't care what people think amd expresses himself in a way that everyone can see! I don't mind gauges as long as you can't fit, like, a cucumber through them. Tattoos can be cool and sexy as long as they aren't excessive and they have a point to them. Lip piercings aren't really my thing but some guys can pull them off.