Umm... all right: I am the most liberal Christian you will ever, ever meet. And not even I would ever say "Jesus was a drunkard, so obviously we can all drink."
Did Jesus drink? Probably, in my opinion. Jesus was accused of being a drunkard in Matthew 11:19 [The Son of Man came eating and drinking, and they say, 'Here is a glutton and a drunkard, a friend of tax collectors and "sinners."]. Accusations like that may have been designed to discredit Jesus, when in fact it really only brings more credit to his character. Jesus was here for the common people of everyday activities, and he moved among them. Most likely he would have also partaken in activities of the day that would have involved drinking and eating (remember that the term "glutton" actually only means "one who overeats on occasion").
Don't get me wrong.. I don't mind drinking, I think drinking is fine, although I myself have put it aside in more recent times. However, to justify it through Jesus? Give me a break...
It is actually mostly just in modern American religion that the consumption of alcohol was a "sin". As a Jew, Jesus would not have been prohibited from drinking alcohol, and wine was an extremely common beverage. It stands to reason that yes, Jesus drank.. as did many people.
But that isn't to say "Because Jesus may have done it, we should all do it, and Jesus was a drunkard". Instead, all it says is "Jesus stood side by side with the common people," and that in my opinion is a good thing of great value.
Anyway... drinking, like anything else, should be done in moderation. Anything done to excess can often be negative. It's just a matter of judgment.
Your friends' argument however is shallow and empty with very little to back it up.