Cut three fingers off a latex glove. Triple wrap your shit. You know where to stick it. Just kidding. In my experience, security personnel at music festivals aren't looking for drugs, just guns and knives. You can hide your stash in many places, your luggage, your socks, etc., since they don't search very thoroughly, but that may depend on the festival. Now, if you get pulled over by a cop on your way there, that may be a different story. Pro tip: don't go to a festival in a hippie van or look like an obvious druggie. Cops may be sitting along the road right before the festival site.