6. Now ask him a question, any question to engage his brain "what did you have for breakfast?" or "do know know what the time is?" it may sound silly, but that split second while he's thinking you unleash with all you've got on his jaw, and then GTFO of there. The other thing you can try (dangerous because you're not looking at him) is to change your gaze over his shoulder and put an expession of "what the hell is that!?" to try to get him to look over his shoulder to check out what you're looking at and then BAM - see above.
Kind of reminds me of a great troll I saw on Sherdog recently. Was a completely unrelated thread but after about a page two guys were arguing. Turns out they lived near each other so one of them said I'll meet you down the park and beat the shit out of you. The other guy goes down there and is posting that he's waiting, I'm wearing a yellow tshirt, you're ****** etc. The other guy goes 'oh I've got a stomach ache, I would have beaten you though', was a classic, I'll try and find it.