Maybe he was staring at you because he enjoyed your singing. The only way to know for sure is to ask him.
he may like you as more than a friend
It means his friend just said something along the lines of "Bro, that chick is checking you out."
If he is your friend he probably has a small crush on you but it won't last for long. If he is not a friend he probably does not like you):
lol most likely
Maybe he lied and he does like you.
The guy is probably making her uncomfortable, staring at her like that. Staring is rude.
ignore and mind your business
it probaly means that the guy you liked told him something about you it could be good it could be bad you never know.Or the guy that's staring at you likes you
it depends on the type of guy. but usally when a boy does this, that really means he likes you.
If you still notice him looking or staring at you. Or if he still asks a friend of yours or him about you.
He wants to get in your pants.
It may mean that his friend is trying to tell him that you're staring. Or that the girl he likes/talks about is looking his way.