Ok theres this dude on facebook I dont like and hes fuckin ugly how do I tell him to leave me alone!

try this:

Stop or Cancel Pending Friend Requests In Facebook

You can easily block or restrict users to send any friend request or invitation in yours profile .

To do this all you need is just go to ‘Settings‘ at the top of your screen, then go to privacy and go to the ‘Block person‘ section. Type in there name and then block them, that way the friend request is cancelled. You can then Un-block them straight away if you wanted too, and this would NOT re-add them again.