Is it illegal to have alcohol in Canada underaged.?

Ok so i have been goin to a bunch of partys lately. Mostly house partys (im in grade 10) and most of them have alcohol. What my question is is. Is it illegal for a minor to have alcohol on them? like in thier bag or something. One of my friends says he was walkin to a party when a cop drove up to him, the cop found the booze and only asked him to dump it out and let him go. So is there laws against that? whats the penalty/fine. I dont plan on carrying alcohol out in the middle of the street im just curious because i do sometimes take part in the drinking. Thx in advance :D