I disagree with both previous posters
first, why are you complaining you couldn`t use canned opener on that girl? canned openers can fail a lot of times, but befriending someone whos a friend of your friend hardly fails, you know?
second, that was a bad neg(really common mistake when you`re starting, we've all been there)
negs have to be playfull, lowering the girl`s value in a PLAYFULL manner, that means, if the girl got offended, you did it wrong and it backfired! your friend didn`t do anything wrong, in fact, he amoged you with reason
if had done it right the girl would react in a positive manner and he wouldnt feel any need to block you, in fact, he`d probably end up leaving you both alone as she would probably turn completely to you
negs are subtle, you also have got to have the feel of the thing, if you`re dealing with a girl thats very playful to you, you will be able to pull this kind of thing off, but you have to remember it also comes to how you deliver it, if you didnt even started talking to her, best advice would be to avoid opening with a neg, or using it very carefully, you`ve got to have social inteligence on this, bro, the game is not a science where you just go there and throw your shots then collect the goods
I also don`t know much about this 3 seconds to laugh after a neg, normally it is kinda instantaneous as the girl get shocked on how you playful mock her(maybe an advanced pua can pull this, but you know, 3 seconds its more than enough time for awkwardness in a social interaction)
now, what you shouldve done was get into their conversation with her normally, being in a seductive playful state, after theres some confort in the interation the neg will be much more easily clicked right
Ill leave you a of Russell Brand that I saw in the videos section, I think it may help on the neg thing
http://www.youtube.com/watch?v=F79vH7lIuig <- he interviewing mila jovovich