San Fermin. Most people who run after the bulls are stupid drunk tourists, and some people who know what they are doing. About the ethics on this, I think bullfighting is def barbaric (and I believe my opinion is shared by the majority of people) but I think running with bull is ok, lol. Just something dangerous and that you shouldn't do when you're drunk. I always get worried when I see that the bulls fall in the streets, but they are supposed to have design something to avoid that from happening.
Other than that it's supposed to be good fun to be there by this time of the year. I have never been in San Fermines and they say it's like I'm party virgin, lol. I gotta go there some time.