Have you ever wondered how you can tell if a girl/guy likes you or not?

I have. I can’t tell if he likes me. He’s been flirting and flirting, but our relationship is strictly “Friends”.
He sits near me in a few classes. He tries to get my attention by throwing his pen on the floor like he accidently dropped it….That’s such a “chick move”. He asks me to pick it up for him although there are other people much closer then I am to the pen. So cheesy!

I asked him one day if he liked me. He said “Whoa, where would you get a crazy idea like that?”
“Well, let’s see, you throw your pen my way and refuse to let anyone else pick it up, you flirt continually with me, you ask my friends if I talk about you, and you always say that you “hate” me.”
He is getting a little sweaty. “No no no, you’ve got it all wrong. That stuff probably seems like that when it really isn’t.”
That doesn’t even make any sense.
“I don’t like you, I can never like you…no wait i’m lying i don’t hate you…you’re cute.No wait…â€?