How do I tell him?

Listen to the kid. Just tell him. I am very blunt with men I just tell them like it is.

Whatever his name is. You can start with. John Doe I have to be honest I just don't think we have much in common. Your boring.

I went on a date with a guy we met at a bar for a drink. He told corny jokes and slapped my arm the whole time. When it was time to go home he walked me to my car and asked if he could call me again. I said to tell you the truth NO. Then I proceeded with can I be honest. And said yes, I said "all night you told corny jokes and slapped my arm and I hate that and most girls do. So let me give you some advice just be yourself with the next girl you meet. He actually thanked me and said I appreciate your honesty, he said no girl has ever been that up front with me and I would rather the truth than to be blown off again.
So go for the honesty. It really is the best policy. And a sure way to get rid of the dork.

Ok I've been in the problem before sadly. Anyway the thing you should do is just tell him and do it fast. But if ur not into that then just send him a e-mail that way you don't have to worry about being interrupted and ur thoughts are all there.