There are a few legends behind why every year Tommy Trojan get wound in duct tape. I come from a family that has had a few generations go through USC and I have heard a few different reasons why Tommy is dressed in duct tape during the UCLA vs. USC football game week. I originally heard from my dad that UCLA had a few students who got a helicopter and tried to dump blue and gold paint on Tommy, but because of the rotor wash and their bad aim, they were unable to get Tommy with the paint. The other story I heard was that they tired to use cow manure, and instead got a lot of it in the helicopter because of the rotor wash. I think I even heard a variation where the helicopter crashed, but I find that hard to believe.
The fact is that this legend has become very much a part of folklore on the campus of USC. Every year the Trojan Knights camp out in front of Tommy to make sure that nothing happens to him. Also, every year he is wrapped up in duct tape. These two fact keep this legend going. The other reason that they legend is still popular is the fact that we would like to think that we are that much better than people from UCLA, and that these stupid plans and actions are signs of our superiority. The thing is I also know a few people who go to UCLA.
The way their story goes, they succeed in getting Tommy with either the paint, the manure, and in one case both, and that it was because of this success that Tommy is wrapped in duct tape every year. At USC we like to think we are taking precautions from keep this from ever working even though UCLA has failed on numerous occasions to try to do something to Tommy.
Another important fact is that the legend is popular to both people at USC, and UCLA, but probably not even know in other school that do not play either school in sports. This means that they legends around Tommy and the duct tape are continued and popular among a small group of people who go to either school.