Guy that is pissy I don't like him.?

[Lurch]

Hmm...As the creepy stalker guy in my own right I have been thinking about this one.

I know what would have chased me away.

Stampede or charge him away. You have to confront him directly and always in a public place.
Draw him a picture and put circles within circles then dot each boy you date within that you have dated the ones you would have married as the inner most circles, and the lower quality guys farther out then friend zone guys you might have dated. Then a circle for weirdo stalkers and put him and any other stalkers in it.

Now if you wish it to end shame his man card if he is a man. Say that there has never been a proper initiation to what he seems to want which is to date you. No sweet hellos, flowers, chocolates, movie dinner dates. Just him watching, and making cruel comments about things that are none of his business. Not really adding any value to your life as a friend, or even a agreeable acquaintance. Tell him that is a very poor way to get attention.
Tell him if he is really that caught up on you to let one week pass and then ask you out on a date in the proper way. Explain this is not a yes or even a maybe. That his behavior has hurt his chances. And the delivery of the request for a date must be better than perfect, and even then he may still get a no.

After all this if you want to have anything to do with him you will contact him not the other way around.
And he is to stop stalking/crushing on you. Then if he is a crazy fool that will not leave you alone block his accounts and delete any comments he makes.

Again you asked how to get him to leave you alone. In high school if any of the girls I like had done this I may have ran away. Conditions in my home life made it impossible to date. So the friend zone was all I could ever hope for.

He may be more complex than you think and a nice enough guy to date.
But then again he may just be another creep and he needs to be confronted any way you look at it.
There may be some danger or risk in meeting him alone so take a quite girl friend with you. Someone over 200lbs that can handle herself.