It's weird I think I know of the guy that ddosed you.. He talks to me a lot, and ddoses a lot of game hacking sites, i was like wtf dude?
One kid using some program like LOIC to try and down a server is pretty hilarious. It wouldn't even have a effect. Unless by some extremely small chance your friend has successfully compiled a botnet and distributed it to enough people he can't do anything.
I don't know, I told him to stop and he did. I doubt you want him to prove it to you. Unless you do want him to ddos you again, for a longer period of time? I'm sure something can be arranged. (it was down for 7 minutes for me, the rest was really fucking slow)